Its a pretty fun trail, not too challenging but still lots of fun stuff. Lots to explore.
57 freeway exit Lambert/Carbon Canyon head east toward Chino Hills. Carbon Canyon Regional park will be on your right hand side. You can park there and access any of the trails in the area. after parking, follow Carbon Canyon Road past the park and the trailhead should be on the right hand side marked by a sign for Chino Hills State Park. There are several other trails in the area, and they are marked by signs.
http://www.singletracks.com/item.php?c=1&i=2819