hello,
Are you using this on a Windows plat form?
Anyways the Mysql Manual should be able to help you please check out http://www.mysql.com/doc/en/User_Account_Management.html.
You need to restart the database for the changes to take affect. just keep this in mid as it might cause you some trouble when testing the permissions.
If you are using windows the default is to have no root password but only allow the system be to accessed from the localhost meaning that you are only able to access the database some the local computer that you are on and not remotly.
hope tihs helps,
- justin