To generate a context class and entity classes for your model, open the model in the designer, right-click on the designer surface, and select 'Update Model from Database...', 'Generate Database from Model...', or 'Add Code Generation Item...'.
'Add Code Generation Item...' will do the trick. You should basically choose and add one or more T4 templates to actually generate the entities. More info here. Also take a look at this answer. It might help to make things clear.