get to your favourite NYC/NJ Crossing.
if it is Geo Washington -
Take rt 80 West until you see signs for the Garden State Parkway and follow Andy's directions from there.
if it is the Lincoln Tunnel -
Follow the road exiting the lincoln tunnels, and bear left. Once you got around the monster ramp with NYC skyline on your right - stay in the middle lane. What you are looking for is Rt 3 West. Again. Once on Rt 3 West, continue until you see the Garden State Parkway South, and follow his directions from there.
If it is the Holland Tunnel -
Once you exit the tunnel. Bear left. It's going to expand into 5 lanes. Stay in the left center 2 lanes. The road is going to split multiple times - look for signs leading to Secaucus, the Lincoln Tunnel and Rt3. Once you get on Rt 3 West - continue on it till you see the Garden State Parkway, and head south on it, and follow andy's direx from there.