Follow Mountain Highway all the way to - you guessed it - the seventh switchback and look for the entrance to Seventh Secret. The trail is marked with a wooden sign that's lassoed to a tree.
The trail starts with a steep, rocky roll-in that acts a filter for the trail. If this move makes you uncomfortable, think about trying one of Fromme's less ambitious trails. As you continue down the trail prepare yourself for some awkward, old-school corners that have been made semi-sustainable through heavy rock armoring.
Tight, awkward corners are broken up by fast-paced traversing singletrack. There are occasional (optional) skinnies and rock roll-over features. It's recommended to take a good look at any and all features that you're considering before attempting.
At the bottom of the trail, follow a little boardwalk out to the road.