If you are a project admin, you can log into your Trac instance, select the Admin link in the top nav bar, then go to the Permissions link on the left. To change a user's permissions, type the username of your user into the Subject field. Next, select the permission you would like them to have added.

Permissions for any group that the user is in are added to the user-specific permissions for that user. By default, a user is in the "authenticated" and "anonymous" groups, since no one can access ProjectLocker instances without authenticating. If you'd like to customize permissions for the whole team, you can either add them to "authenticated" or create a new group for your team with basic permissions and adjust per user as needed.