My 70 Dart

be sure you place tack welds before you go any farther.

you don't want to concentrate to much heat in one area or you will warp your metal.

It looks like you might have your wire speed to high and its ramming the wire into the steel......try turning the feed down a bit and maybe turning the heat up a bit.

then try welding in a side to side motion about a 1/8" pattern to "bridge weld it".

your only going to probably be able to weld for about 3 seconds at a time unless your moving at a very fast pace.

the cheaper welder on thin gauge metal with little welding experience tend to want to burn through.

good luck.....and don't be afraid to give it a couple practice runs....find whatever metal you can to practice on and get yourself familiar with the feel of the welder until you feel comfortable with welding on the car.