You need to purchase a trail pass at the trailhead, $5 daily or $30 annual as of 2019.
You'll be in dense forest for most of the ride on a 4,000 acre preserve with not many landmarks so you might get a feeling of being lost in the woods but the one-way trail system is well marked and well maintained to keep it up to IMBA standards.
The trailhead is at the south end of the parking lot with an informational kiosk. Buy a trail pass to use the trails. Starting out on doubletrack, the route quickly drops into 9 miles of fast flowing singletrack. The terrain is rolling hills with a few sharp climbs but no real technical sections.