No worries, you'll do fine solo!
Check the local bike shops. Both Mountain Bike Heaven and Bike & Bean have websites. Buy a book, the family will have something to read & get charged up over. When you buy your Red Rock Pass (government found a way to take your money, $10 or so) you can get the free map but it's not much in the way of quality.
Your biggest problem will be determining trail difficulty - I've accidentally got on trails too difficult, and I've accidentally puttered around for hours looking for real trail to ride. I've never had problems with getting lost, for Bell Rock, Cathedral Rock etc. make pretty good landmarks.