Once you've got your method tested out a bit on some scrap, it's time to do the actual weld. In this photo I am doing just a simple butt weld on some square stock. We've already ground down the edges of the surfaces that are going to be welded so that the seem where they meet makes a small "v".
We are basically just taking the welder and making our sewing motion across the top of the seem. It's ideal to weld from the bottom of the stock up to the top, pushing the weld forward with the tip of the gun, however that isn't always comfortable or a good way to start learning. In the beginning it's perfectly fine to weld in whatever direction/position that is comfortable and that works for you.
Once we finished welding the pipe we were left with a big bump where the filler came in. You can leave that if you like, or you can grind it flat depending on what you are using the metal for. Once we ground it down we found once side where the weld didn't penetrate properly. (See photo 3.) That means that we need to have more power and more wire to fill in the weld. We went back and redid the weld so that it was properly joined.