The Munich Agreement was made signed as Hitler wanted to take Sudetenland in 1938. Hitler encouraged the Sudeten Nazis to unify with Germany, and the Sudeten Nazis agreed. Hitler told them to make a lie that they were being ill-treated by the Czechoslovakia's government, not only that the Nazis of Sudetenland started riots and force the government to give Germany Sudetenland, so Hitler made and excuse to invade Czechoslovakia.
After that Hitler made plans to invade Czechoslovakia. Neville Chamberlain appeased Hitler. Chamberlain was afraid that this would lead into a war, so in September 15, 1938, Hitler and Chamberlain met and they worked out a plan with the French Prime Minister saying the parts where there are 50% or more Germans should be given to Germany (Hitler first demanded this). So on the 22nd Chamberlain told Hitler that it was confirmed. But Hitler changed his mind already by then, now he wanted the whole of Sudetenland by the first October.
So on the 29th of September 1938 one last attempt was made to solve the crisis, Mussolini, Hitler, Chamberlain and Daladier (French Prime Minister) met in Munich and it was decided that Sudetenland would be given to Germany.
You might be wondering, how can Hitler take over Sudetenland that easy? Well, Hitler began to build up his armed forces, in 1935 he introduced conscription (calling up men to the army). This actually broke the Treaty of Versailles, but Britain and France let him get away with it. Britain and France couldn't physically stop him from doing it because they were following the policy of appeasement. So Hitler has his own army, he have a strong backup by then.
Humans are never satisfied! Hitler not only has Sudetenland, he also has Rhineland and Austria, but now he demanded Czechoslovakia!...