Can't assign roles in admin panel
Looks like you're on /admin/people/permissions, which is the page for configuring permissions per role. You want to be on /admin/people/permissions/roles, which is the page for configuring the roles themselves. If you can access /admin/people/permissions/roles, you'll be able to add more roles there.

If you get an 'Access Denied' error when you try to access that page:


Go back to /admin/people/permissions.
Make sure you've given the 'administrator' role all permissions.
Go to /user.
Click the 'Edit' tab.
Scroll down and make sure your account has the role 'administrator'.