I am relatively new to mountain biking and this is my home course.  It is fantastic.  Lots of variety with some easier trails (Mainline), some moderate trails (Cascara, Southern Traverse), and some harder trails (Red Alder, Cedar).  Most trails involve some moderate descent/ascent and tons of roots.  If you're looking for something super beginner friendly, you can park in the main parking lot off of Paradise Valley rd.  You can then take mainline about a mile and a half to the intersection with the Red Alder trail.  From here you can turn back, and you really won't hit anything technical.  If you continue on mainline up, it gets more technical (though still pretty doable for a novice) until the end of the mainline trail.