NJMP is one of the best tracks on the east coast to run on. Everything up there was top notch when I stopped running like 2 years ago.
There are several groups that used to run there that are good. EMRA, IMG, NASA and SCCA are great.
Start out in the HPDEs with instructors and go through their sign offs to get comfortable before just jumping in. If you have no experience at all and are just getting into it I would suggest finding a group in your area that Autocrosses. Autocrossing teaches you the basics of car control at lower speeds with usually less consequences, ie. hitting cones rather than gaurdrails or fences.
SCCA and NASA are 2 of the best groups in Jersey to run HPDE with good instructors and a little more structured.
All that being said be prepared to spend lots of money and get hooked after the first time. It was 4 of the best years in my life running with SCCA, EMRA and IMG up and down the east coast. I learned a lot about setups, handling and car control and had a blast.
2009 EMRA Time Trail Tuner Under Champion
2010 EMRA Time Trail Tuner Over Champion
2001 Ford Focus ZX3 S2 with PWSC 265 whp