users memberships premium

hi
i'm totally new on wordpress and your service
i was looking for a plugin to hide any contents I want from the users and showing the hidden ones only for the logged in users.
so, i really don't know much about the service your providing and if you can help me in this case.
more infos..
i'm streaming movies online, and i want to let the visitors to see everything but the part of the video, so they can make sure that i have what they want but they have to login first
and also i'm planning to make offers and stuff like that

how can you help me ?