It's not easy. A long drawn out process. Tanning kits have all you need . Scrape and soak hides for several days, test ph constantly, change water solution etc etc. Go ahead and try if you have the time. Buying 1 hide may be cheaper for you in the long run
If you get all the fat off, just coating the flesh side with borax should do the trick. Put a layer of borax on it and let it sit till it's dry. The borax doesn't tan the hide but it will preserve it so it doesn't rot.