How can i get BlackBerry messenger on my blackbery play book ?(is is possable because i dont have 3g?

You need to run the Playbook via a Blackberry handset to get the Blackberry features, such as Blackberry mail, Blackberry messenger, etc. You would have to have a Blackberry account on the Blackberry phone, the cost of which would be determined by the network you sign up to. Without a Blackberry phone, the Playbook can't do very much. I assume you have some sort of Blackberry handset, although you say you don't have 3g, so perhaps you don't have one.