The best part about natural, holistic remedies is that they are cheap, easy to find and easy to use.
Topically means, apply it on the skin, as opposed to orally which means you eat/drink it. Probiotics can be found it any drug store in the vitamin section. The pill bottle with say "Probiotics"
IU means international units. Its simply another type of measurement. In any case, the bottle will tell you a recommended daily intake, so you don't need to worry about knowing what IU means in particular.
Aloe Vera plants are succulents. The larger the thorns, the better the plant. You can buy an aloe plant at any herbal shop and even some drug stores. To apply it, trim off a small bit of the leaf. Cut off the thorns. Then pull open the leaf to expose the jelly interior. Then rub it onto the wound. It soothes, cools, and prevents infection.
Organic tea tree oil is sold in tinctures at Whole Foods, drug stores, or herbal shops. Put a few drops on a cotton ball and dab it on the wound. It can sting, but if it burns, you need to dilute it with water.