Razorlighter

I had only ever played GRAW 2 single player campaign but a friend of mine who likes this type of game has just sorted out live etc. Lastnight we spent 2 hours trying to work out how we play 2 player online campaign coop to no avail. We tried starting clans and inviting each other but couldn't even seem to do that, all I want is to know how to start a 2 player campaign coop with a friend, didn't think it could be that difficult, please advise and make a couple of old gamers happy! Appologise in advance for being idiots!