The username and the password for the admin is controlled in the globals file with these tow variables:
$WAGLOBAL_Admin_UserName = "" ;
$WAGLOBAL_Admin_Password = "" ;
As a simple test you can just put in the word test into both of these, then save the page and make sure it is uploaded to the live site where you are testing this. When you browse to your powerstore files you will go into the admin folder like this:
If you are not able to successfully login please explain what is occurring when you try.