I tried to take a picture of my lights but I don't have a live camera battery anywhere in the house. Sorry. A picture is going to be worth a thousand words in this case.
Looking at mine, there is the pre-attached crash structure bracket (looks like an upside down T with holes in the horizontal part) that I attached the light bracket and light housing onto. The adjustable (up and down) bracket that the light housing itself attaches to, IIRC, was already attached to the light housing as well.