Desktop Manager 6 doesn't support connecting the PlayBook via bluetooth. In fact, you can't even backup the PlayBook. The only support this far is simply transferring files. There's a Desktop Manager 7 in beta right now that might have more PlayBook support. I might sign up to test it out in Beta Zone.
is it possible to create a backup from playbook over wifi or bluetooth?
Actually, you could MANUALLY backup files (music, video, photos, docs, etc) by copy/drag/drop from Windows' Explorer or some mac version using Wifi-sharing.