I bought these for attaching my rear bumper:
I made stand-offs out of short pieces of 2"X4" tube steel to go between my bumper and the mounting tabs. I welded those to the mounting tabs then bolted the plates to the frame, then I centered up my bumper on the Jeep, clamped it and tack welded it, then took it off to finish weld it.
Here is my rear bumper thread:
I didn't take any pictures of the process but you may get a better idea of how I did it by looking at the pictures.
I attached my front bumper by cutting up the stock front bumper to make mounting tabs from it. Since it bolts on differently then the rear you don't have to make stand-offs. Just weld them straight to the bumper. Or use your imagination and come up with your own way of doing it.
Post pics if you can...