From the parking area, take Le Relai
up, then hop on this at intersection A9 on the map.
Most of it is switchbacking singletrack and a relatively easily pedal up the mountain. There's rocky sections, so it does require some good bike-handling to navigate. It's well-designed and uses lots of curbs and pendulum drops to help use momentum in your favor as you move up the hill.
Make sure you keep to the right to stay on Tapis Magique as you're crossing intersections A1 and A2 while pedaling uphill. If you're riding downhill, keep to the left, obviously.
If riding uphill, this trail ends at intersection A3. If riding this downhill, it starts at A3, obviously.