This is basically two loops, one short and one long, with a couple connectors between them. The eastern loop is more interesting, but very short. The area retains water and the ground can be very soft. There is one climb that will get your heart rate up, but it is short and not very appealing. The powerlines cut a very wide swath through what would otherwise be a nice little patch of woods in suburbia. There's a lot of foot traffic, especially close to the nature center and by the lake. Nothing technical. Very leafy, even by Maryland standards. Cedarville is better for a beginner and Rosaryville is better for anyone else.
From Rte 5. S. of 495, take Old Branch to Thrift. Follow Thrift through the park and take a right into the parking lot at the nature center.
http://www.singletracks.com/item.php?c=1&i=3677