1) Log into subdomain on the WordPress side as 'Admin' (using pre-selected username and password - see Making a Subdomain )
2) On the left widget go to 'Users' and select 'Add New'
3) Set username, email, and password as desired
4) Add the new user by clicking on 'Add New User'
5) If this is the first user account, find the 'Your site is currently showing the under construction page. To go live click here' banner near the top of the page and 'click there'
6) Log out of the WordPress instantiation