The job is not that hard to do. Borrow the bearing removal tool from Advanced Auto.
The only slightly tricky part is after you pull the pin on your rear end to remove the C clip. Be careful not to turn the wheels or the gears inside may fall. Take a good close look at what you have there just in case they do, and make sure that the shim is put back where it belongs. In fact block up the wheel that you are not working on to help you not let that happen.
If your rear end oil is fresh just catch it and put it back in. Knowing that you are 21. When you do this job you will know that you can do anything. It is not hard, just a bit scary for a novice. Go for it.