Using phpMyAdmin
If your web server has phpMyAdmin installed, you may follow these instructions to create your WordPress username and database.

Note: These instructions are written for phpMyAdmin 2.6.0; the phpMyAdmin user interface can vary slightly between versions.

If a database relating to WordPress does not already exist in the Database dropdown on the left, create one:
Choose a name for your WordPress database ('wordpress' or 'blog' are good), enter it in the Create new database field, and click Create.
Click the Home icon in the upper left to return to the main page, then click Privileges. If a user relating to WordPress does not already exist in the list of users, create one:
Click Add a new User.
Chose a username for WordPress ('wordpress' is good) and enter it in the User name field. (Be sure Use text field: is selected from the dropdown.)
Choose a difficult-to-guess password (ideally containing a combination of upper- and lower-case letters, numbers, and symbols), and enter it in the Password field. (Be sure Use text field: is selected from the dropdown.) Re-enter the password in the Re-type field.
Write down the username and password you chose.
Leave all options under Global privileges at their defaults.
Click Go.
Return to the Privileges screen and click the Check privileges icon on the user you've just created for WordPress. In the Database-specific privileges section, select the database you've just created for WordPress under the Add privileges to the following database dropdown. The page will refresh with privileges for that database. Click Check All to select all privileges, and click Go.
On the resulting page, make note of the host name listed after Server: at the top of the page. (This will usually be localhost.)

define('DB_NAME', 'wordpress');    // The name of the database
define('DB_USER', 'username');    // Your MySQL username
define('*********', 'password'); // ...and password
define('localhost', 'localhost');    // 99% chance you won't need to change this value