In a nutshell, you will zero rifle at 100 yards, then reset your turret knobs to zero. Then you dial up the mils or moa needed for whatever range you are shooting.
You will want to use a ballistic calculator to calculate your drop at distances. I usually print one out at 20 yard intervals.
If you are using a handheld device (iphone etc), you can use one of many apps on it to do the calcs.
Essential gear is a laser rangefinder, unless you are confined to known-distance ranges.
Here's a free online calculator that is fairly user-friendly. Play with it a bit and it's fairly intuitive.
http://bergerbullets.com/ballistics/
