MIG Welding.
But I don't think you need to weld it up. You can utilize panel bonding adhesive to fix up the holes. Place an overlapping panel behind the hole and adhere it using the panel bond adhesive then use a prep paint to fill it. It works well. Eastwood's no weld hole repair is yet another option for quick repair. I haven't used it yet but found good reviews online.
I suggest that you learn a bit basics of welding. It might be useful future. If you have a basic welding knowledge, then you can fix the holes with an MIG welder. You can learn basics from online, youtube is a free wellspring of learning. You can rely on them for knowledge. Likewise, there are many welding certifications courses available, I have found one such from an online portal,
tool and die course certification in 5 days. If you wish to learn, you can either enroll in such courses or do it online.