I'm trying to create a page where all my users are listed, and every movie they've added to their account.

My UserController index def

def index
  @users = User.all
  if logged_in?
    @user = User.find(session[:user_id])
    @movies = @user.movies
  end
end

And my user index.html.haml

#content#users
  - @users.each do |user|
    %li
      = link_to user.name, user
      .movie
      - @movies.each do |movie|
        .movie-frame
          = movie.title
          = image_tag(movie.image)

At the moment the -@movies.each do shows all the movies that are added to my database, it does this for every user. And not specifically the movies that that user has in his account. How do I show each movie for each user?

So you'll need a join table between Movies and Users. Something like UserMovie is a standard naming scheme for that. You could also give them a name like Favorite.

In essence you'll do this:

class User < ActiveRecord::Base
  has_many :user_movies
  has_many :movies, through: :user_movies
end

class UserMovie < ActiveRecord::Base
  belongs_to :movie
  belongs_to :user
end

class Movie < ActiveRecord::Base
  has_many :user_movies
  has_many :users, through: :user_movies
end

This lets you access @user.movies to get their movies and you can also get a list of a movie's users (people who favorited it for example) by doing @movie.users

You will need some mechanism to create the join table records, but if you check out the screencast I did on hearts/favoriting/liking, that's pretty much exactly what you'll be doing for that.