Step 4: Bondo!
For small dents, sand 2 inches all around the dent down to bare metal (use really rough sandpaper, maybe 120 grit). Make sure the metal part is really rough. Then get a can of Bondo - you can find it everywhere - and mix it up on a clean, non-porous surface. Slap it on the dent, cover the whole area past flush.
Try not to get bubbles mixed in, these look terrible. Then you sand the Bondo back down to flush, using really big sanding strokes to make it even with the whole surface. Use progressively finer sand paper to get a nice smooth end product. You shouldn't be able to feel where the Bondo blends into the car.