Treating a cut on the bottom of a toe is just like treating a cut anywhere else, with one significant difference. Since so much pressure is put on them during the day, they need extra protection to keep from getting re-opened or infected. Here's how to do it.
Examine the cut. Is it deep or shallow? Is it long or short? Is it clean, or dirty? is there anything in it? Is it bleeding and, if so, how badly.
If the cut is bleeding badly, the first matter is to stop the blood flow. Wrap a bandage moderately tightly around it, and elevate the foot by putting it up on a table or chair. Sterile gauze is the best way to stop the bleeding, but a paper towel or even a T-shirt will do in a pinch.
Once the bleeding has slowed, or if it was not bad to begin with, walk to the bathroom, taking care to put as little pressure on the wound as possible. If possible, have someone else support you so you don't have to walk on the toe.
Clean the cut with a cloth. Wipe gently around the surrounding area and the cut itself, cleaning away any blood or dirt. Pat it dry.
Sterilize the cut with an antiseptic. This will hurt, but you need to do it to avoid an infection. Rubbing alcohol works well. Hydrogen peroxide is excellent, but it will hurt a lot.
Put on some antibiotic ointment, such as Neosporin. Be sure to cover the cut completely.
Apply a Band-aid, or other adhesive bandage. Make sure that the pad covers the wound, and wrap the bandage all the way around the toe.
Wrap a layer of bandage tape around the bandage. This will serve to provide some added cushioning to the wound, and also stop the bandage from moving around.
Change the bandage every morning and every evening. Cut it off with a scissors, wash the wound gently, and re-apply the antibiotic ointment. Then, put on a new bandage.
Particularly if you do a lot of walking, consider wearing two pairs of socks until the cut has healed somewhat. This will cushion it, making it less likely that you will irritate and re-open it.
If the wound gets red or purple and swollen, or starts to ooze pus, go to the doctor as soon as possible. You probably have an infection.