This is another of those simple jobs that I am posting just so people can see how easy it (usually) is.

View of the bottom of the used skid.
The tab at the top goes onto studs in the front cross brace
The side brackets go to welded nuts in the uniframe

View of the top of the skid (normally against the truck). Note the angle iron reinforcing.

The plastic plugs that hold the front of the engine splash guard in place must be removed. The skid will hold the splash guard in place.
The studs are supposed to screw into threaded hole in the bottom of the front cross-member. If the holes on your Jeep are not threaded and you don't have a tapping set you can drill the holes a bit bigger and put nuts on the top of the studs (just make sure you don't knock them out when positioning the skid). If your holes are threaded and you can't spin the studs in by hand then the easiest way to do it is to spin two nuts a little ways onto the bottom of the stud and turn the lower one tight against the upper one. You can then insert the stud and use a wrench on the lower nut to turn the stud. Once the stud is in place you put a wrench on each nut and twist them away from each other to loosen them.
With the studs are in place you fit the splash guard over them and then lift the skid into place. It is easiest if you have a buddy handy to thread the rear bolts on while you hold the skid, but one person can do it.
Once the rear bolts are finger tight you put nuts on the studs and then tighten everything up.

You now have a handy-dandy front skid, useful for finding short stumps in tall grass or Toyota Tercels in deep mud holes.