Buy a welder, some rods and a good (read automatic) helmet. Wear thick leather gloves and a fairly non-flammable jacket (otherwise, you’ll get sunburn from the UV rays from the arc).
Get some uncoated steel of the appropriate thickness and practice, practice, practice. Don’t use any galvanized or cad-plated metal as it will make toxic fumes when welded. And ideally, work outside.
You want a stick welder, not a wire-feed or MIG since you’ll be welding thicker metal. You should be able to grab one off Craigslist cheaply.