Instructions
Log into your PSN account through your PS3 console or set up an account if you don't have one.
Access the PlayStation Store through the "Games" or "PlayStation Network" menu on the PS3 cross media bar. Choose "Games" from the menu on the left and press "X."
Select "PS1 Classics" and press "X" to view the library of PS1 games available. Select a game and press "X" to view details.
Check the price of the game and the download size. Make sure you have enough available space on your PS3's hard drive to store a game.
Choose "Buy Now" and confirm your purchase. Follow the prompts to enter payment information. The game will begin downloading once your transaction is completed.
Choose "Download in the Background" to continue the download as you return to the cross media bar and play another game or watch a movie on the PS3. Make sure your PS3 remains powered on during the entire download process.