The trailhead is across the main road from the Grant Hill Loop parking lot. The trail is wide and rocky and climbs for half a mile before coming to a junction. Take the left. The right will get you back to down to the main road close to Cunningham campground, but the running to the left is more fun.
Stay on the singletrack for the next 3 miles as it takes you mostly downhill back to Cunningham campground. The trail swoops, and turns and crosses small creeks then dead ends at the main road. The Cunningham campground is to the right.