Do you even know how to weld??? If not then you should pay someone to do it for you.
I love it when I see sub par welds, it just proves certain things should be left to people who have the skill to do it right.
If you want to do it yourself I would suggest that you practice on your old floor pan or other sheetmetal of the same gauge and do your prep work before you even turn the welder on.
The best machine for a novice welder to learn on is the Miller [auto set 180] it costs about a grand or more for an equivalent machine but it will put you in the ballpark, just set it to the gauge metal you are welding and it adjusts the heat and wire feed speed accordingly and will help you concentrate on technique IE: penetration, angle, and travel.
If you butcher it and then it needs to be repaired then you just cost yourself double what the job would have cost had you just paid a professional in the first place.
I'm not trying to discourage you from trying this on your own, I just want you to have a fighting chance because I don't know what your abilities are.
On a good note MIG is the easiest to learn, I taught a monkey how to do it in less than an hour.
Good luck in whatever way you go, RZ.