You're not giving me much to go on here. Maybe some clarification is necessary?:

1) Which model AR do you own? You say it's an "M4", but I can't tell whether it or not it's a flattop.

2) Are you sure it's not a "Millett" red dot sight? I googled "Millon" and come up empty, unless it's some kind of knockoff of a "Millett"?

If your rifle's a flattop and the sight is indeed a Millett, should be relatively simple to attach the sight by means of 30mm "Weaver-style" rings. Check milletsights.com for more info - you may want to request an owner's manual, anyway?

If your rifle has the fixed "Carry Handle" sights, there are Picatinny rails made for those as well. One you attach the rail (which are available from numerous manufacturers), same mounting system as you'd use with the flattop, but expect a much higher mount.