There's no easy/fast way to get to this section of the Backbone Trail. Option one is to drive up Little Sycamore Canyon (L.A. County)/Yerba Buena (Ventura County) from Mulholland Hwy and park at the Mishe Mokwa trailhead.
Option two is to park at the Encinal Canyon trailhead and take the Backbone Trail: Encincal Canyon Rd to Etz Meloy Bypass
The trail itself is really fun! It's well maintained - no overgrown vegetation or deep trenches - and the grade remains gentle for the most of it with some exceptions. There are two bailout sections that will lead you back to the main road (Yerba Buena) and there is an access to a (steep) fire road that takes you to Yellow Hill; an overlook peak.
The views of the Pacific Ocean and the mountains are amazing! And you'll quickly notice that you are indeed in the highest parts of the Santa Monica Mountains - Sandstone Peak (3,000+ feet) is just a few miles away.
The trail is 100% singletrack and is good for someone who's learning to mountain bike. There are not too many, if any, technical sections.