Drivetrain Replaced tranny but not shifting...

Got a new tranny put it, however, now it doesn't shift. It basically in in neutral. I am a little bit clueless when it comes to transmissions in general, so I asked a friend (who fancies himself a mechanic) to take a look. He said that the gears were "not connected". Also, the whole exhaust is still off.

I guess I just need to know how to explain it to a real mechanic (which would also help me estimate costs).

Thanks!