can anyone briefly explain the basics to filling in holes on the metal parts of a car?

i switched my spoiler to a type r style spoiler and i need to fill in two holes. what do you recomend i use for this, bondo? any other product u recomend? also, my type r style spoiler has a led light so the hole where the wires comes through, i dont wanna completely cover, i want to have a small section of it open for the wire, but only enough to have the wire and to be covered by the spoiler. how should i go about doing that?

also, i have a couple dents in my quarter panel, they arent super deep or sharp, but its kinda spread across my right quarter panel, and 2 small ones are by the body line. i used a ding king dent popper to get it out some but its not perfect.. can i use a body filler or bondo to smoothen out the surface or is that gonna be too thick and the filler will crack or be unsmooth..

any help, advice, pictures, suggestion are welcome..thanks homies

 

I would weld the holes ant then wipe some putty on it after you grind them flat. You should only need a thin layer of putty if done right.

 

you can allso use fiberglass resin and cloth ,if you dont weld or cant get to a shop to have them welded up

or for welding it up ,you just make a little patch go from the under side and tack it in place ,then just tack it a few more times to make sure it welded good ,make sure you dont go to fast when welding it (warping can happen ) grind it smooth and plastic filler

id personal use fiberglass jelly ,but its up to you

good luck

 

what would be best for holes in the engine bay? (wire tuck/shave)