An outline for a speech is fairly simple once you decide what your 2 or 3 points are going to be. "How to do makeup" is a bit broad, but here are some ideas.
If you're speaking only about how to apply makeup, your points will be in chronological order--the order in which you would apply each element. For example:
II. Applying foundation
A. Start with a clean face
B. Begin at the forehead (or wherever)
III. Applying eye makeup
IV. Applying blush
For each of these points, or whatever other points you might choose, simply list the steps as you normally do them, including any tips or advice you'd like to give along the way.
If you're covering more than just how to apply makeup, perhaps you should consider something more like this: Types of makeup, Applying makeup, Removing makeup. It really doesn't matter what you choose--though your teacher may certainly have given you more instruction, and that's what you should follow, of course. Just select those major points and start filling in the gaps. This should be much easier than some other topic because it's one you're probably somewhat familiar with, at least.
Once you've written the outline, think of creative ways to begin and end your presentation. Perhaps something funny or practical or surprising would work for this topic. (Do you know what many brands of makeup have in them?!? Quite shocking, some of them.)
The key to this speech, I think, is to start with what you know and then fill in the blanks. I wish you all the best on your presentation!