It will take a fair bit of practice to get the settings right and used to it....

Different thickness metals require more heat so you turn up the amps....too much and you will blow holes in the metal, not enough and you won't get the penetration and will have a cold weld sat on top of the metal. The weld should melt into the metal and fill the gap (should have a blue tinge round the weld if you have decent penetration). Then the wire speed. If you have it set too slow then it will weld like bird shit, spatter like fook and weld the end of the wire to the tip of the torch. Get it too fast and you will feel the wire pushing back on the torch as it hits the metal before it's had chance to melt....

Best thing to do is get some bits of metal and practice. If you are welding body panels then you have to do it a bit at a time to prevent the panel warping as it's only thin tin...