Instructions
Turn on your PlayStation 3 console by pressing the "Power" button on the front of the device. When you are into the PS3 main menu, scroll to the far left-hand side of the cross-media bar (XMB) menu and highlight the "Users" icon.
Click on "Create New Users" and type your new username into the text box provided. Once you are finished creating your username, press the "OK" button.
Scroll up to the new user account you have just created and press the "X" button to select it. When it asks you if you want to currently log in as the selected user, click the "Yes" button. This will log you out of your primary account into the secondary account you have created in Step 2.
Scroll to the far-right side of the XMB menu and highlight the "PlayStation Network" icon. Select the "Sign Up for PlayStation Network" icon and complete the enrollment process. It will ask you to enter personal information, such as date of birth, full name, home address, email address and password. You will also be prompted to create a new online ID and password for the PlayStation Network.
Press the "Create Account" button after you have entered all the information to finalize the creation of your new PlayStation Network ID. Once you begin to play the online games, your new gamertag will appear.