Santa Maria Road is a "private" road. Nevertheless, it's in the middle of a public park area. Just wanted to mention it.
There's nothing too exiting about this trail. From the end of Santa Maria Canyon Trail, turn left and climb uphill on Santa Maria Road. After 0.25 miles, you'll hit a "No Trespassing" sign on the road, look to the right, and you'll see the trailhead.
The trail is hard-packed dirt, a bit overgrown, but mostly fun and flowy. There is a cliff side that you'll pass to your left at some point, which is a good place to stop and check out the view of Topanga Canyon.