Thread:Project:Support desk/For *computer-novices*: Access denied for user 'user'@'localhost' (using password: YES)/reply (5)

It's in "Database settings" step, and only visible if the "Use the same account as for installation " checkbox is unchecked (If that box is checked, you probably don't have to worry about it). However re-reading what you wrote, that sounds less like the issue. So you should probably ignore what i said above ;)

It more sounds like you put a database username/pass that doesn't have sufficient permission to create new databases. When mediawiki tries to log into your db with that username, mysql doesn't let it do the stuff i needs to do. (if this is on your local computer, the "root" user generally has all permissions. If you're using a hosting company, you should contact your host and ask them what db user is allowed to create new databases)