I'm new to ATV's and my right rear tire is either flat, or awfully low. my question is is this a diy job or, do I need to take it somewhere to have it fixed? Thanks foe any help!    

slime from walmart will do a pretty good job of fixing a flat, cost is around $7.00.  

It's pretty easy to fix a flat so long as the flat is not in the sidewall area. Spray some soapy water all over the tire and air it up. Look for the hole by finding the bubbling area. Once you've located your puncture, you can use a tire plug kit to plug it up. Same as you would use on a car. Air it up and you should be good to go again. When you end up replacing you tires, go with a 6 ply tire. Hope this helps.