Do you know anything about welding? You're supposed to make little overlapping circles, kind of like you're stitching it together.
As for heat (voltage), too hot and it'll burn holes. Too cold and it'll make a tall mound instead of being flattish.
Wire speed, if it's too slow, the heat will melt the wire up near the gun tip and you won't get a steady run. If it's too fast, the gun will push back in your hand.
Travel speed, go about this fast
. You're on your own for that one.
You'll have to kind of tweak the three together. The hotter you weld, generally the faster the wire speed has to be. Travel speed should be constant.