To drive fast on back roads you do it the same way you would drive fast on other roads.
However you would need to watch more closely for any vehicles that may be coming out of driveways, yards etc.
And also watch out for any possible curves or vehicles coming around the corners.
When on back roads you should drive a bit slower than you normally would on other roads and especially if it's on a dirt road.
Dirt roads can get sandy and cause you to lose control of the vehicle so keep both hands on the steering wheel.