in the garage the button to the left that says "drop" should be under the skin's selection thing. if you press that your car drops, ideally you wnt your car to have compressed suspension, then on the rebound, you want it to stop moving right as you get to where it usually is. so you want to ajust the damper to allow that generally. with the demo cars you dont have rebound, but what that would do, is you would ajust those two together so it is the right ratio to get the suspension stopped right at the top of the rebound.
what i have noticed for rebound, (lets say it is in the back for this example) is if you put more rebound then regular damper then it tends to generally oversteer more. not every setup will have the suspension stop moving at the top of the rebound.
i fail at explaining, so PM me if you are still having troubles.