How do I properly tape my shotgun?

I bought some camo tape for my shotgun for duck hunting. I am not sure of how to put it on correctly. Sorry for sounding like a complete novice but I don't know how else to describe it, on my barrel the sights stick up on this little rail, and there are gaps between the rail and the barrel. I am not sure of whether to tape over it or go through the holes. (I have a Maverick M88 if you don't know what I mean and want to google it.) Do I want to oil the gun or do any sort of special treatment before I start to tape it as well? Thanks for the help!