Instructions
Go to the PSN website (see Resources) and sign in to your user account by entering your PSN user ID and password into the boxes provided.
Click the "Report Behavior" link on the right side of the PSN website or enter the address to the PSN complaint form webpage in your browser's address bar. The PSN complaint form will appear, with two input boxes.
Input your sign-in ID into the top box and the cheater's ID into the bottom box. Click the "Next" button.
Click "Cheating," which is the third button from the left.
Click the "Submit" button to finalize the complaint.