I'm just showing one way of a quick Diy repair without using a welder and patch metal this is a fairly easy process with little experience and tools needed, there are much better ways of doing this (welding on a jobber panel or patching with metal) but this is just a very cheep way no welding or experience in metal work needed and if the vehicle is rust proofed after the repairs and every season afterwards it will last for many years.
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Tools:

Grinder or rotary tool
Hammer
Paint brush
Paint scraper
Palm sander (optional)
Mixing board (old piece of sheet metal)
Sanding block (block of wood)
Body File

Materials:

Grinding Disks
Rust Mort (if you can't remove all the rust)
Short or long stand fiber glass filler (bondo Glass)
Fiber glass cloth for cars not boats
Body filler (Polyester body filler)
Spot putty
Wax paper (the stuff you use in the kitchen)
Sand paper 80, 120, 240 grit
Primer (use the stuff for autos only)
Top coat (color match paint)
Clear coat