These are Mountain bike trails developed by the Central NH NEMBA chapter. Check out this map on their website (http://www.cnhnemba.org/2012/12/updated-map-for-page-hill.html)
Starting at the parking lot follow a short trail into the woods and then you can turn left or right. I suggest taking a left onto Bear Claw, ride it to Hard Hat. That gets you to an access road which will run under power lines for a while. Don't miss the left onto "The Dude Abides". That's an awesome trail with lots of rocky sections, some natural and some man made.
After the Dude decent via Spring which can be quite a bit muddy as I found out.
When you get back to the power lines take a right (the left won't get you very far) and keep riding this access road to Hydra. The access road is a fast ride over exposed rock. Hydra will be your trail back to Bear Claw and the parking lot. It's easy to miss so keep your eyes open. If you go too far you'll be back where Hard Hat comes out.