1. Push your finger into the back of the sanding paper or cloth and make small circular swirls. About an inch or two swirls is enough. Use this circular motion all around the damaged area until you see no more distinguishing marks, from the damage. You can wipe the area occasionally to inspect. (For deeper scratches and gouges, you may need to begin with about a 320 grit sanding sponge or even a grinder for really deep cuts. Finish with progressively finer paper until you get to a satin finish.)
2. Once all of the marks have been removed and you have a satin finish, apply some polish with a cloth. Then use the buffing wheel in small circular motions as you did with the sand paper. Don't push too hard, just let the polisher do the work. You will see the area turn black with the polish. Keep working it until the entire area is black. Now take a cloth and wipe away the black. It should be very shiny and no marks. You may see some uneven polishing due to the small swirls, but at this point you are just trying to get the damaged area smooth.
3. Now that you have the area free of scrapes and scratches, apply more polish. Now you will need the larger wheel with the soft fluffy sides. Use longer, more even strokes and you will see all of the small imperfections go away.
4. Now you have a great looking shiny area on your bullbar and may want to polish the rest of it. Be careful of one important thing. The area closest to the road (skirt) may be somewhat pitted from rocks and gravel, based on the miles and driving you do. If pitted, you will get that black polish in the pits and they will be more obvious. You can still polish this area, but you need to be aware of this effect and use the polish sparingly on the skirt.