There's a very obvious path for a short circular route straight from the car park. If you bear left to start with, this gives the dog a chance to charge around and work off some energy before you walk closer to the road on the way back.  It's fenced off but I'm always wary about fences on a walk I don't do all the time. The 20 minute circular route is very clear and easy to follow.   There are other paths also, and you can extend the walk as far as Calke or the other way to a different part of the National Forest. Be aware that you'll need to cross busy roads on the extended walks.