Your trash is not burning on the bottom because you need to poke some holes in the barrel to let in some air near the sides and bottom. Fire needs air in order to burn. Here is what I do: Go to the hardware store and buy an awl. It is like a large nail and is used as a tool to punch holes in metal. Turn the barrel on its side and hammer the awl (you will probably need a sledge hammer) to poke holes in a ring around the barrel, about two inches from the bottom, with the holes spaced about five inches apart. When you are done with that, then do the same thing higher up on the barrel, about halfway between the top and bottom. This should be enough to get you started. There are some other things I would swear by, if you want to do even better:
1. If possible, keep your trash in paper grocery sacks. They will fit in the bottom of a kitchen garbage can and then when burn, they give you an edge of paper to light.
2. There is no need to burn every day. When you take out the trash to the barrel, toss in the trash and then use a piece of plywood as a lid on the barrel (when you are not burning) to keep the trash dry. When the barrel is full, it is time to burn the trash. Do not pack the trash tightly into the barrel. You want there to be gaps of space in among the trash, which will help it burn by letting air flow in. If you have cardboard boxes to burn, break them down and then stand them up vertically within the barrel. Set them on one side of the barrel and let your trash fill up the other side until you are ready to burn.
3. When you light the trash, do not just light a top piece with a lighter. It will go out three-quarters of the time and you will have to light it again. The real key is to get some trash lit down near the bottom. I swear by kitchen matches. Keep a box near your back door and just grab it on the way out when you take out your trash. Then at the barrel, strike a match and reach down pretty deep into the barrel with it and set it to any paper you can find among the trash. Then just let go of the match and let it fall in among the trash. The reason you want start the fire from deep down is that flames burn upward and will spread quickly instead of burning out if they hit a damp spot. After quite a while, your vent holes in the barrel will enlarge from rust and you will be able to light from outside the barrel by picking one of the larger holes where you can see a piece of paper, and poke a lit match through the hole.
4. If you can find a grate to put on top of the barrel when you are burning, it will keep larger ash and burning papers from flying out, drastically reducing fire risks.
5. When you burn your trash instead of having pickup service, it’s easy to become a packrat. It is something you want to stay on top of, and besides taking care of the garbage, make an effort not to let unwanted items and junk accumulate around the yard and in the garage because you are not sure what to do with it. It is easy to throw away the unneeded or unuseful in town because you toss it in the trash cart and close the lid and it is whisked away. When you burn, you have to deal with the unneeded more directly, and it can be hard. But you will need to remember that anything you no longer need and that can’t be used is nothing but trash to you and needs to be burned with the trash. When it comes time to do some closet cleaning, we usually start carrying out loads and build a pile out back. At some point while we are carrying out loads to the pile, someone will put a match it.
5. If you have a family, you will want to put some thought into chores, responsibilities and who takes out the trash and who burns it, or is allowed to burn it under supervision and without supervision.