From your last picture you have a bit of "Spatter" which means your wire speed is slightly to high.
I could be wrong but from the picture you maybe welding the wrong way.... meaning welding into the pool..
e.g if your right handed, you have your two pieces of metal clamped together to hold them. Put a tack each end. Then start from the right welding left, holding your torch on a slight angle. This way also you can see the join you need to be welding.
Lefthanded, go from left to right.
You can tell by listening to your car if it is running rightly or wrongly..... and so you can with a welder.
The sound needs to be a nice Crackling sound, not spitting ( wire speed to fast) or a fizzing sort of noise (when wire speed to slow). I would suggest 5-6 mm steel to start with, you can press the trigger on a piece whilst you play with the controls to get the sound right