Clean the surface of the stainless steel with an industrial degreaser to remove surface oils.
Feed the wire to the torch. Insert the wire through the guide tube and over the roller. Use a screwdriver to align the wire with the end of the wire liner. Push the wire into the liner for a few centimeters, after which it should feed into the liner without requiring additional force.
Tighten the tensioner so the wire stops slipping, but not enough that the wire feed motor slows.
Fine-tune the wire speed and power settings of the weld, depending on the thickness of the weld you want to obtain and your desired degree of wire penetration into the stainless steel. Thicker welds and more penetration require higher wire speeds and higher voltage currents, while the opposite is true for thinner welds. For best results, use your TIG welder at different settings to weld scrap metal and wire, and thus determine which speed and voltage best delivers the results that you want.
Use both hands to hold the MIG torch. Angle the torch about 20 degrees from the vertical, with the shroud angled forward. Hold the contact tip about 6-10 mm from the metal to be welded, while allowing the carbon wire to touch the metal.
Fire the MIG torch. Consult the manufacturer's instructions for specific tips on how to control the motion of the torch. For thicker metals and wires, you can use a zig-zag motion without curves. For thinner materials, use a zig-zag motion with curves, to avoid the possibility of the metal blowing through.