So, you finally got the bike and all the gear. Now... Where can you ride it?
If you you're one of those lucky people with a big yard, you can ride right from your garage and don't need to register your bike (as long as you stay on your property). Also, it's a good idea if you are going to be riding on someone elses private property that you make sure you have the owner's written permission to do so. The rest of us, however, will normally ride on public land, which requires state registration.
If you plan on riding in New Hampshire, check out the New Hampshire Bureau of Trails. There are several well-known, legal ATV and Dirt Bike riding areas in New Hampshire. The most popular riding area is Clough State Park, due to its convient location. (Be sure that you are registered - the fine is $108 for an unregistered machine.) http://www.nhatv.com/
If you live in Maine, check out the Bureau of Parks and Lands. There are quite a few good riding areas.