How to put games on Sony Psp 3004...how to put games in sd card?

so i am using sony psp 3004.and i want to play games by installing the games in the memory card .my memory card capacity is 4gb .now i dont know that i am on the official firmware of sony.maybe i m .my first question is -

1. does my sony psp has officially or custom firmware,details are-

system software version 6.60

Mac address-5C:6D:20:C6:7E:B5

if this is the official firmware ,then i am still playing games on my memory card -like assasian creed bloodlines,wolverine,taken 6,swat,dead to rights.

but i have heard that the games cannot be installed without a custom firmware,if the games cannot be played without a custom firmware then how am i playing these games .

if my psp has official version then what is the procedure to install the games like gta vice city etc.

please guide me....