Get What You Want

If you want someone to do/say something:
Focus on them, and imagine them saying or doing what ever it is you want them to do/say. Really imagine there voice in your head saying what ever it is you want them to say, and their mouth movements as they talk. Also think of the movements they will make while saying or doing what ever you want them to do. It takes a few minutes and a lot of concentration, but it does work.

If you want something to happen in a certain spot:
Lets say you want a teacher to be absent. Focus on the area from which they would come into your line of sight, and imagine a substitute teacher there instead. This will require more time and concentration then just getting some one to say something, and requires a lot of practice. After you get the hang of it, its pretty easy.