1st. Lets get a well built wire brush (good) or a grinder (best) and get to work on removing any paint or mill scale. You want to brush or grind down to shiny metal.
2nd. If you're using gas, don't use the flux core wire. for just gas, rub a little acetone on the bare metal after grinding. This gives me my prettiest welds. Do the same for flux.
3rd looks like you're getting the idea of heat. Start hot and as you go along (depending on gauge or if you're staying in the area) back of the hit just a touch. This will help with your learning curve and you'll get better as you go along. It's better to be a little hot than cold and risk a break. Too hot will compromise the weld as well by weakening the parent material around it which is more common on thinner materials.
last, your wire speed it too high. Your beads are close to even, damn good if you're a beginner. Slow that feed down till it's too slow, go a quarter inch and stop. Check your penetration and heat. If it's good you can start speeding up. If not, keep adjusting. Find some flat stuff too.
