Containment was the foreign policy of trying to keep communism from spreading, without ending it in the countries it already exists in. The picture is supposed to represent the Soviet Union being locked up in that room.
Formation of NATO
NATO was an alliance of many of the Western Powers. The picture represents leaders of the countries sitting and discussing the terms to form the alliance.
The Marshall Plan was the idea that the U.S would rebuild post-war Europe by providing financial aid. The picture represents President Truman signing bills that would providing loans to European countries that were affected by the war.