http://www.panynj.gov/aviation/lgrpfram.htm This should take you to the post you are looking for but it is expensive if you are parking for more then say two or three days - might be cheaper to take a car service. I don't belive that you can make reservations for parking that is one I have never heard of before
We've parked at the National Car Rental lot for $17 per day...it was very convienent, right across the bridge and a shuttle is always going over. You can also try airpark or avistar, both are offsight & cost less