Turning the top turret (elevation turret) counterclockwise will move the strike of the round up .25MOA per 100yds, per click. That equates to .25" at 100yards, .50" at 200yds, 1.25" at 500yds, 2.5" at 1000yds, etc.
Turning the right side turret (windage turret) counterclockwise will move the strike of the round to the right .25MOA per 100yds, per click.
The reticle is also set up in MOA's. It can be used to both range unknown distance targets of a known size, and to allow for hold-offs (Kentucky windage and Tennessee elevation).
For instance, say that you have a 100yd zero and that your dope for 400yds is 8MOA. You could dial in 8MOA, or alternatively, you could hold over and use the hashmark labelled "8" as your new crosshair.
For ranging, I'm assuming that the reticle is "true" MOA and not "shooter's" MOA. First thing to do is to accurately measure the target with the reticle and take of note of what figure you get. This number will be your measurement in MOA. At a minimum, you need to get it down to tenths, although hundredths are way better and thousandths are the shit.
The formula for ranging and unknown distance target with a true MOA reticle is:
Measure target in inches with range in yards: Multiply the size of the target in inches by the constant of 95.5. Take the answer and divide it by the MOA reading you get when measuring the target. The answer will be your target's range in yards.
Measure target in inches with range in meters: Size of the target in inches multiplied by 87.32. Divide by MOA measurement of target, answer will be range to the target in meters.
Measure target in centimeters with range in meters: Size of the target in centimeters multiplied by 34.37. Divide by MOA measurement of target, answer will be range to the target in meters.
Clear as mud?
Personally, if he is actually Italian and not American, he might have been better served with a mil/mil setup, and not an MOA/MOA. If he hasn't purchased it yet, have him get a setup with .1mil adjustments and a mil reticle, such as the Gen-2 XR. The .1mil adjustment will move the strike of the round 1cm per 100 meters.......he might be move comfortable with that setup.