All great advice by above members.
Brand name MIG. highest amp 110V you can afford. (like Miller or Lincoln) with Gas. Take a class. Read.
Thin metal is hard for beginner. Use .030 wire and back up weld with copper pipe flattened out.
If I could say this a 100 times I would:
Clean the metal nice and shinning clean near weld on both sides. Clean a good ground spot on both sides for ground clamp. Have really good lighting and a good auto darken helmet. Buy some old cheap fenders or hood off of any old vehicle. Cut a bunch of real thin slots with a angle grinder (.040 or .060 blade) and weld them up again. Do 50 of them over several days or weeks. Use all kinds of feed and amp settings and tip angles until you see what it takes. Then cut out pieces and weld them back on (butt weld). In other words: Practice.
It is best to "spot weld" a whole bunch or spots all along the seam. Don't do two near each other. When you are done it's basically a bunch of connected tacks. Wait for cool, spot way away from previous and cool each with air nozzle. Go SLOW, I say REAL SLOW. If you think you are slow, slow down some more. Take all day if you want. If you warp the panel. You have cost yourself 100's of dollars. It will not warp if each spot is cooled before next. Hammering on the weld is another topic.
Grinding the welds is almost as dangerous as welding. You can warp your fine welding job in a New York minute.
So grind a little, move around and blow air on it.
Stick is not hard to learn. It's for big stuff and is 220V. It's a lot of fun too. No cleaning of metal, no warping.
I took a community college welding class as mentioned by F18.
Tons of YouTubes on it.
