Raising garage to pour concrete

I am in need of help in figuring how to safely raise a 2 car garage in the mountains. I want to pour a concrete pad under the garage then set the footprint on top of the concrete. Right now the floor is dirt and it is on 8 6"x6" concrete footers which is raising it 4" from the ground so you are able to look under the wall and see the outside. I want to turn it into a hunting cabin and need to support and level the garage. The footers have sunk into the ground leaving the garage off level.
I would like to see if anyone has any good ideas for me, I am very handi but have not done this before and I am just a bit concerned about doing it right. I want to make sure I reinforce the concrete at the exterior to support the walls so the concrete won't crack.

Thanks

300 x 300mm trenches on the outside to create beams is the way to go. 12mm trench mesh. 10mm thick pad for the floor with 7mm concrete reinforcement mesh with 200mm squares. Best to use an excavator and laser level to do the foundations. about 5.6 cubic metres of concrete and you are done.

There is a bit more to it, such as the 100mm of washed sand that you would be advised to put under where the main pad will be, and you can consider whether you want plastic underneath too.

I would also definitley recommend a person who knows how to screed and float the slab to do the final laying.