First thing you need to do is go buy a bow square.

If you look around, you'll likely find a square in a set with nock pliers and a set of hex wrenches. You're gonna need all of those goodies. If you find the set, it'll be the best 20 bucks you've ever spent. Then do what sho-me outlined for you. The only thing I'd add is to make sure your tiller - how the strength of your limbs are balanced with each other - is right.

With your new bow square, measure from the each end of your riser, at the junction with the limbs, and check to make sure the measurement is the same on each end. You can change the measurement by adjusting the limb bolts - backing off to raise the string, or cranking down to lower it. So, if one end is higher than the other, you can either tighten the limb bolt on the high end, or back off the limb bolt on the low end.

When you've made sure the tiller is even, then you can start in working on your nock height. As for that, I can't tell you exactly where you'll wind up. A lot depends on what diameter arrows you shoot, what type of cam(s) is on your bow, how you grip the bow, what kind of rest you're using... All I can say for sure is, shooting 3-under generally demands a slightly higher nockset than shooting split fingers.

It really IS gratifying to see others who choose to shoot with their God given fingers instead of using mechanical contraptions. I hope you do well with that shorty bow. You might find it helpful to drop a finger when you get the bow drawn and use a 2-under release.