i am 23 and would be applying there in 2 months. i dont have any other country / state licence.
what is 6 hour drving course? i already know driving. so even then i would have to take the course?
what happens in the behind the wheel test?

If you already know how to drive, then the simplest way is to get a booklet from the DMV (or download one online if available) study for the written test and then take the test. The test in NJ is harder than NY in my opinion.
After you pass the written test you can then schedule a road test. You can use a driving school to do the test or if you have a car available (friend or relative) you can take the test with that car.
You should know how to parallel park and be familiar with the rules of the road.
take the written test, which isnt easy. you might have to do it about 6-8 times before passing.

have a midsize to small car to take test in. Car must have proper paperwork and sticker. you must have that owner of the car with you and they must be driving not you

on the driving test. do not speed whatsoever. even if someone is tailgating you. Go slow but not to slow.

Make sure both you and instructor has that seatbelt on. Remember you have to tell him to put it on he wont do it on his own.

keep 2 hands on the wheel.

come to a complete stop at the stop sign, very important

Your parellel parking must be pretty good the first time or he could fail you. Make sure you practice this alot before you go for testing