Overview

Admin

To show only objects for the current user in admin, try: User manager snippet.
To set the user when saving a model in admin, see Customisation, User…

Authentication

See User Authentication …

Model

To link a model to the current user, see:

To set the user when saving a model in a view, see forms.
To set the user when saving a model in admin, see Customisation, User.

View

To prevent access to a view unless the user is logged in etc… see User Authentication.