There are procedures that are described in the PS3 when you try to add friends and involve sending a message to someone
Chat with our AI personalities
click on player you want to invite. and press invite to game
To invite friends in Skate 3 first go to the online challenge map, then go to Freeskate. From there go to a skate park and choose party. From there choose invite friends and choose the fiends to invite.
You Go to friends and click 'Invite Friends and get starcoins'
Just ask. As simple as that.
sign in then at the bottom of your room there should be a button that says invite friends get rox click that and there u go!