The User Profiles page shows all the current profiles active on the system and what actions they are capable of/prohibited from performing. Check the corresponding box with respect to the profile and action, and then press "Save Changes" to update the permission settings. The permissions are sorted alphabetically and can be filtered by their "Pretty name".
All creation/deletion/modification of User Profiles is done from this screen.
To set profile permissions with respect to other users and not actions see the User Matrix page.
For more description about the specific range, control and context of each individual permission setting, see User Profile Permissions.