multi db installtion error . Showing access denied

Its showing

“Houston, we have a problem!

Looks like you need to create your new db’s! If you’re lucky, this link still works – click me

Database Error: Access denied for user ‘username’@’localhost’ to database ‘username_global’ “

1)when i extracted multi-db plugin i did not get a db-config.php file . I just edited db-config-sample-256.php and renamed it

2) Should i add any user and password to all databases i created before i upload? If yes how can I ?

3) In step 3 at line 16 should i use my actual server ip or just ?