Head out on the Gateway Trail from the parking lot and enjoy the views as you wind through the beginning of the route. It crosses a few old roads, so just continue on the singletrack you started on.
As you progress farther on the trail you'll encounter a couple slightly steep, rocky sections that contain some technical turns. Later in the trail you'll find a sign on a tree signifying the Zap Trail turnoff on your right, ignore it. As you curl around through the dense forest the trail will t-bone another old road. Continue across the road and take the Gateway Trail (the one on the right) as the sign identifies.
Finally, you'll be delivered straight into the Tunnel Trail. Enjoy!