The United States implemented the policy of containment in two major ways. One way was military and the other was done via diplomatic and economic means.
In terms of military operations, the United States implemented the policy of containment in many instances. For example, the US used military power to try to end communist insurgencies in Turkey and Greece as well as in Vietnam. The US also used military force in the Korean War and the threat of military force in the Cuban Missile Crisis.
However, the US also used economics and diplomacy to contain communism. The most outstanding example of this sort of containment was the Marshall Plan. By aiding the countries of Western Europe, the US was helping them economically as well as putting some diplomatic pressure on them to side with the US against the Soviet Union.
The policy of aiding Greece and Turkey with over $900 million in military aid during their communist insurgencies became known as the Truman Doctrine, and it was followed time and time again in countries like El Salvador, Nicaragua, Guatemala, and Peru, as well as a number of countries in Africa and perhaps most notably, in Afghanistan in the 1980s. It was a very cheap and effective way to practice containment.
The US also implemented containment using "Collective Security" arrangements, such as the formation of the NATO military alliance in Western Europe, which adopted a philosophy of "An attack on one is an attack on all". This safeguarded Europe from Soviet expansion because they did not want to start World War III with nuclear armed countries. It was very successful. We copied this idea in Asia with the ANZUS alliance, joining Australia and New Zealand with the US in a NATO-like military partnership.