Plugging emblem holes in fenders

Well it's your car so take your time letting it cool between tacks. The copper backing plate also acts as a heat sink to draw heat away from the weld area. You can hit it with a blow off gun if you want to speed things up. Every time you finish a tack check your wire. Cut the ball off the end and keep a consistent stick out of the nozzle.

Does your machine have auto set, or a wire speed/voltage chart? That'll get you in the ballpark for the wire size your using. After you get used to mig you'll be able to hear what the machine wants.