Welding questions

I'm trying to do some welding and have been successful to an extent, but welding sheet metal is eluding me. I have a thermal arc 210 with 30 gauge wire and argon gas 75/25 mix. In the first pic is a fender I got at a swap meet. what kind of welder did this? The second photo is of my welder,can someone tell me the best settings for welding sheet metal? Any help would be greatly appreciated