This is a lead in from some of our other "beginners TIG welding" articles. Once you have started getting your technique and hand positions down on a piece of flat metal. Then make sure your beads are looking satisfactory (and uniform) and then you can move to laying some welds on a simple butt joint. The key when learning, is to make sure you have the two pieces clamped together tightly before welding. The larger the gap in your butt joint, the harder it will be for a beginner to fill the joint, and make a nice weld. I like to clamp the piece at both ends, then put small tack welds on each end before running your beads. Make sure you watch your puddle as you weld the joint, and be sure it doesn't get too large and start blowing the gap apart. First try running beads on these joints in between practice runs on flat metal. Eventually you will start to mimic your better weld beads from your flat stock to your butt joints.
Remember Practice Makes Perfect!