The tips ar all prettt much in that error message.
It's telling you that either the database name is wrong, the database doesn't exist, or your database user doesn't have any permissions set ofr that database.
this is something that can be fixed up pretty easily in most control pnales (your hosting control panle, not the WordPress admin area), so try that first and if you get stuck as your hosting company and they'll be able to walk you through it.