Looks pretty straight forward. Personally, I would
1. install the 2 brackets on the frame, not tight but not loose.
2. build the center section, loosely as well then tighten and measure (corner to corner in a X pattern) so it is square.
3. attach to the frame brackets and tighten, again measure from solid points equal on each side to ensure it is square on the vehicle.
4. attach the headlamp guards.
There are multiple ways of doing it. Pictures tell a lot.
Count the bolts, nuts, and washers according to size.
front view as you look at it on the truck
The above picture you can see how the frame brackets would mate up to the frame. I would guess it would bolt to the lower portion of the frame. Also, guess there are holes on the frame for them to bolt to, 2 on each side.
view as if you are the vehicle...
Below shows how the uprights bolt to the frame brackets.