Dispersed camping in National Forests means camping outside of a designated campground. This includes that fact there are not going to be any services available. There will be NO water, restrooms, trash removal, tables, fire pits, etc.
Camping in this way brings with it more responsibilities than would be associated with staying in an improved campground. The main responsibility is that you Leave No Trace. This is a common theme you’ll find when i reference dispersed camping. Requirements of dispersed camping include being self-contained, camp for no more than a specified number of days and then must move a certain minimum distance away, must camp a certain number of feet from streams and water sources.
The best way to find out exactly what areas are open to dispersed camping and the rules that apply to that area is to contact the nearest Forest Service office for the area you are visiting.