There is a sight window on the engine case on the lowest part of the side of the engine below the oil fill cap. You have to get a friend to hold the bike as level as possible or you have to prop it...
Look on the what would be passenger side of the quad towards the bottom/side of the engine.. There is a little clear glass viewing area where the oil is..
The drain plug is a large one, slightly to the rear of the center of the engine. When you remove it, be careful not to lose the screen, spring, and o-ring inside of it. Clean the screen and plug in...