Mike,

Although a search about walk-back tuning would be better I'll do a quickie for you.

To start you suspend a piece of string from your target, top to bottom. I have to use rope as my old eyes can't see string anymore. Then you sight in your bow at 20 yards adjusting your sight till you are hitting the string.

Then walk back to 30 yards and shoot again, using the same pin.Your arrows will hit lower but centershot is what you're working on. If your arrows are hitting to one side then you adjust your rest slightly in the direction you want your arrows to go. Then do the same thing at 40 yards, assuming you have the skills for it.

Then you go back to 20 yards and start over, adjusting your sight to hit the string. Then go to 30 yards, etc. It's a lot of trial and error and usually minute adjustments to the rest, but when done your rest should be set up on the dynamic center of the bow (the path that the string follows during the shot).

Then you sight your pins in for their respective yardages. Now that you've done this it's time to tune for broadheads, but this is another matter, and more for fine tuning.

As mentioned above Easton's Tuning Guide covers most of this.

Hope this helps some.