Instructions
Play through the Cryptids Island level, until you have some matches and a lantern. You get the matches in a pub in Loch Ness and the lantern from a monk in the Himalayas. Complete these two sections, then go to New Jersey. You can select any of these locations from your helicopter.
Ride the motorcycle down the path, once you land in New Jersey. It's necessary to follow a series of directions to get to the gate. Go right, left, left, right, right, right, left and left when you see any fork in the road, and you'll end up in a small, dark circle.
Click on "Look Around" at the bottom-right of the screen. Go into your inventory and click on the matches, which automatically lights the lantern. Go to the right, and you'll see a gate. Click on it to enter.