I'd start by bore-sighting just like I would a scope. Nice if you have a laser device to do so with but certainly not necessary. I don't... just eye-balling down the barrel works fine for me. I bore-sight at about 30', this dimension isn't critical. If you need to come in further or can go out longer more power to you. You just want to get it on paper with the process. If you're not familiar with bore-sighting just google it or search here (or ask). Chances are it will be on paper from the get-go, but it's always nice to boresight it first, because if it is way off, it's a pain to deal with after the fact.
Then go out to the range, set up your target at your desired zero, and put 3-rounds on target, aiming dead center on your desired impact point. So long as your group is tight (indicating precise fire), you can use it's offset from the bullseye to approximate the red dot adjustments required. For example, if you were zeroing in at 50 yards, each click of the windage/elevation adjusters would be equal to a .5" change in bullet impact (this 1moa adjustment spec is in the manual). If you were zeroing in at 100 yards each click would be equal to a 1" change.
So you check out your group, see it's 3" below the centerline of the bullseye, and 2" to the left of it. If you're at 100 yards, that means you dial in 3 clicks of elevation, and 2 clicks of windage. Shoot 3 more rounds, and if the group is consistent, either confirm you're on target or repeat the process until you are.
