I'm not sure exactly what you are looking for.
There are several books on the hiking and backpacking trails of Yosemite. Some are a little more up-to-date than others. The National Park Service web site for Yosemite has some general information about doing trips in Yosemite. They have a map of all of the trails in Yosemite, and which trailheads feed those trails, and where to go to get a wilderness permit for each district of trailheads. Sometimes they have information on trail conditions. However, most of that information tends to be rather old.
Basically, wilderness permits are free. However, you may want to pay some bucks to get something reserved. Each trail has a daily quota for overnight backpacker use. As long as the permit you ask for will fit within that quota, then it should be free. However, if you are going in prime season to a popular trailhead, and especially if it is on a weekend or holiday, then the daily quota will be taken before you get there. So, if it is important, you try to reserve a permit in advance.
Now, if you are not picky, you can just go to a permit station near your proposed trailhead and ask. Sometimes the quota for the best trails is already filled, but sometimes a daily quota is still open for some ordinary trail right down the road. The web site typically shows information as to which trail quotas are already filled. So, the ones that get booked up far in advance for many sequential days are the most popular trails.
For most of the Yosemite backcountry, bear canisters are required for food storage. So, either you bring your own or else you may choose to rent one (Garcia) at the permit station. Personally, I like to have my food all packed in a canister before I ever leave home, and that way I know it fits. I think the rental canisters are used a lot by people who go only once or twice a year.
Those are the most important parts of getting the trip legal. After that, you just need to know what you are doing as a backpacker.
I've seen guys busted by the backcountry patrol rangers. Either they had no permit, or they were camping someplace improperly, or they had a dog in the backcountry, or some other obvious mistake like that.