What happened in the movie Friday the 13th?

Answer 1

Jason drowned in the 1950s at Camp Crystal Lake and after that even, the camp was closed UNTIL a few decades later when people reopened the camp. All the helpers at the camp get killed off the movie one by one until it is found out that Jason's Mother, Pamela, is the killer. In which, in the end she gets decapitated by the only survivour, Alice. Tramatised by the experience, Alice has the dream that shes still at Camp Crystal Lake when Jason comes out of the lake and almost kills her. Hope this kind of helped :D