If you already have a male rabbit, I would avoid going out and purchasing another male rabbit as bonding two males is more hit and miss than bonding a male / female.
Prior to bonding any rabbit it is really important that you get them neutered. I dont know if your rabbit is neutered, if it is not this done, leave it at least 4 weeks and approach a rescue who should help you bond an already neutered female in with yours. This way the worry of bonding is reduced and you will have back up if you have problems.
If you get the male off the free ads, you will need to get additional accomodation whilst you are waiting for him to be ready following neutering, you iwll have to bond them yourself and if the bonding does not work out you will need to sort out suitable accomodation for an adult rabbit.The rescue route is definately the easier route.