What was going on when I was born?

Pope John Paul II today began a six-day pastoral visit to Britain, the first by a reigning Pope in the 1,900-year history of the papacy. He appealed to Britain and Argentina ''to put aside the weapons of death'' in the Falkland Islands. The war in the South Atlantic prompted John Paul to call for peace again and again as he moved from Gatwick Airport south of London to a mass in Westminster Cathedral to an audience with Queen Elizabeth II at Buckingham Palace to a service for the sick and dying in Southwark Cathedral. At the airport, he fervently urged ''all people of good will to join me in praying for a just and peaceful settlement.''

The Reagan Administration said today that the plan of the Metropolitan Transportation Authority to buy 825 subway cars from Canada violated international trade agreements. And it said that it was considering ''all of our options'' for action against the Canadian Government and the manufacturer. The Administration's views were expressed at a hearing of the Senate Finance Committee by Donald E. deKieffer, general counsel of the Office of the United States Trade Representative. He said the trade agreements had been violated because the financing provided by the Canadian Government was at an interest rate belowthe one set by industrialized countries in the Organization for Economic Cooperation and Development.

British forces have captured Darwin and Goose Green, overrunning the second largest Argentine installation in the Falkland Islands, the Defense Ministry announced tonight. Victory over the well-fortified Argentine garrison of 1,000 men would constitute a major military success for the British a week after the establishment of their first beachhead in the Falklands. And gaining the two settlements, which occupy a small isthmus on the main southern route from the beachhead to Stanley, would carry the added prize for the British of an airstrip, at Goose Green. Later, the Argentine high command issued a communique saying that Argentine ground and air forces were battling to repel British troops trying to secure a position in what was described as heavy fighting around Darwin and Goose Green. The communique said British ground forces had air and naval support. The Argentines first said the British attackers had been beaten back, but later that they had returned with reinforcements and were conducting an active battle around Darwin. (Page 4.)

A masked man drove a car through the glass lobby doors of an I.B.M. building here today and went on a shooting spree, killing two workers and stalking and wounding at least eight others as they cowered in office cubicles and corridors. Seven hours later, after negotiating by telephone with the police, the man emerged from an office in the building and surrendered quietly. Police Chief Bernard Crooke of Montgomery County identified the gunman as Edward Thomas Mann, 38 years old, a former salesman for the International Business Machines Corporation. The chief said that Mr. Mann, who lives in Mitchelville, Md., about 30 miles from here, had been armed with two rifles, a shotgun and a pistol.

The United States Court of Appeals yesterday ordered an end to a civil trial in Federal District Court in Manhattan and expunged the testimony given in it by the Rev. Sun Myung Moon. It also ruled that the testimony could not be used against Mr. Moon in any other civil or criminal case. In its unusual ruling, the court said in addition that the Unification Church, which is headed by Mr. Moon but was not a party in the civil suit, must pay all legal fees incurred by the defendant in the course of the three-year-old case. The church had agreed to this stipulation.

The Budget Committee chairman suggested today that the House of Representatives ''split the difference'' between the Democratic and Republican budget plans it voted down by wide margins early this morning. The chairman, Representative James R. Jones, said his idea got a ''mixed'' reaction at an informal meeting of his committee this afternoon. Under conflicting pressures to increase spending and at the same time bring down the deficit, the House rejected all the budget proposals before it after five days of turbulent maneuvering. The votes early this morning, which ran counter to the pleas of leaders from both parties, signaled the vulnerability of a bipartisan coalition that last year enacted the groundwork for President Reagan's economic program. Lawmakers Are Deeply Divided The rejection of three separate plans in the final hours of the House session reflected a fragmentation that might prevent any budget from being adopted for the fiscal year 1983, which begins Oct. 1. Some Republican moderates and Democratic conservatives defected from the Reagan-backed budget plan, and many Democrats, unhappy with proposed cuts in social spending, voted against their own party's plan.

Hama is a broken city. In the first three weeks of February, Syrian armed forces and local Moslem rebels fought building to building in the alleyways, mosques and covered bazaars of this western city of 180,000 people, the traditional center of religious opposition to the secular Government of President Hafez al-Assad. At the time, the Syrian Government played down the events as a relatively small-scale police operation. The uprising was described in more ominous terms by diplomats in Damascus and by the insurgents here, but it was difficult to establish with certainty what had taken place as long as the Government kept this city sealed off. In the last few weeks, however, the authorities have reopened Hama, 115 miles north of Damascus, to foreign journalists, and the picture that emerges, that of a city half damaged or destroyed, is chilling.

Three Soviet prisoners of the Afghan resistance movement arrived in Switzerland today to be interned by the Swiss Government after being released into the custody of the International Committee of the Red Cross. The negotiations for the release of the prisoners, their transit through Pakistan and the conditions of their internment were conducted by the all-Swiss committee with the Afghan resistance and the Soviet, Swiss and Pakistani Governments. Othmar Uhl, a Swiss Foreign Ministry spokesman, said the internment would cease with the end of hostilities in Afghanistan or after two years, whichever came first.

Prime Minister Lee Kuan Yew today announced a Cabinet shuffle that gives one of his younger ministers full charge of the island's defense.

The national chairman of the Rural Solidarity union, released from internment at the end of April, said in an interview on his father's farm here today that the authorities had tried to undermine the union from within and had never negotiated in good faith. Jan Kulaj, 24 years old, the leader of the farmers' union, appeared healthy after more than four months of solitary confinement, usually in Government villas, and said he had suffered no physical or mental mistreatement. But the tall, burly farmer, sitting at the living-room table of his father's modest home in this remote corner of southeastern Poland, between Rzeszow and Przemysl near the Soviet border, was uncompromising in his adherence to everything that he and Lech Walesa, the chairman of the main workers' union, stood for until they were arrested when martial law was declared Dec 13. 'Our Union Exists' ''Nothing better than our unions can be created,'' he said. ''Our union exists and should be allowed to operate. The unions were created when they became necessary to save the fatherland at a critical period.''

Nicaragua and Honduras said today that at least 200 people had died and about 65,000 had been made homeless in floods described as their worst in nearly 50 years.

A leading Iranian official, in apparent response to concern expressed by Secretary of State Alexander M. Haig Jr., said today that Iran was ''not adventurous'' and did not want to interfere in the flow of Persian Gulf oil to the West. But Hojatolislam Hashemi Rafsanjani, the Speaker of Iran's Parliament and a close aide to Ayatollah Ruhollah Khomeini, said Iran would not accept a cease-fire in its war with Iraq until its conditions were met. He said Iran was demanding the withdrawal of Iraqi forces from all Iranian territory, the payment of Iraqi reparations for war damage and a trial for Saddam Hussein, the Iraqi President.