Kush,
just enter the park, park in the 1st lot on your right and head towards your right down the trail. as long as the resevior is on your left you are heading the right way. head all the way out to the end (1/2-3/4's of the way around the resevior) and turn around. You can't get lost. There is some grueling climbing involved, but its not that bad. just be sure to bring extra tubes, food, and water. There are some maps available. there is also a good book, written by Josh Peirce, called the NJ Ride Guide. it has maps and descriptions of many NJ rides. A place like round Valley is pretty easy to navigate with a simple map and explanation. If you want more details, let me know.
Enjoy