Before you ask a question it's recommended that you try to do some research on your own. A little searching can go a long way.
Anyways
- how-to-enable-x11-forwarding-with-ssh-on-mac-os-x-leopard
- MIT article on the subject
- my Google search
If you can't get it working, I suggest looking at the Super User Q&A forums. Super User is similar to Stack Overflow but it's more geared towards arcane terminal stuff and general computer questions whereas Stack Overflow is more geared towards programming specifically. You might be able to find more knowledgeable people there.