Step 1) On either one of the PSPs start the game which has the Game Sharing feature.
Step 2) Now under the game's main menu, or perhaps under multiplayer, there should be a "Game Share" option. Click it
Step 3) The PSP should now announce that it is "Connecting" and the wifi channel number.
Optional) If the second PSP isn't set to the same wifi channel as the first one ... visit the Network Settings menu and setup an Adhoc connection w/ the same channel number as the first PSP.
Step 4) Now with the second PSP navigate to Game Sharing located under the Game menu on the XMB and click it.
Step 5) Both PSPs should be connected and after a few moments of transfering data from the first PSP to the second the Game Share should be complete and you can then play together.
Now Have Fun!!!!