So you're gonna wanna look up a map about this area. Don't just park where the marker is that is not open land that is private.
The Dyrt site/app map helped zoom in and find the roads. Also this: https://www.fs.usda.gov/r01/dpg/maps-guides. If it is during the week, you can stop by the Ranger office and probably pick up a map.
It's really pretty out here. Make sure your vehicle has decent clearance but nothing too extreme. 2007 Toyota Sequoia with a 1.75 inch lift.
When you get nearby, these grasslands just look for those signs for the roads on the map like 1212, 1215, 1217 etc.