After completing the installation, you can browser your new OCAx site and continue with the basic configuration.
You don't need to do this if you are trying the Virtualbox image.
The Admin can assign profiles to other users. An Admin can also assign the Admin profile to another user. But right now there aren't any users with the Admin role because we've just finished the installation. So, we going to have to assign it to ourselves manually. This is the only time you will have to (or even should) modify the data base directly.
Via the web interface register yourself as a new user. Let's say your username is andy. Now you have to manually alter the database to make your new user 'andy' an Admin. If you're using PhpMyAdmin, look for the SQL tab and execute:
UPDATE user SET is_admin=1 WHERE username = 'andy';