timing belt adjustment on 1991 Volkswagen Jetta

vehicle has a new timing belt but i am being told that its "off time" and that it needs to be adjusted... how much is that going to cost?? is it something i can do myself?? i just replaced the starter myself because i was told that's what it was that was keeping the car from starting...(only starts if you push start it)... but its still doing the same cranks it just doesn't start... "Lady in distress"

Asked by for the 1991 Volkswagen Jetta
Here is a link to the repair info for your car, that should help.