Qualifications
You'll need to get your bachelor's in an education program. If you're planning to teach at the kindergarten or elementary school level, you'll receive training that will prepare you to instruct on a variety of subjects; if you're aiming to teach secondary education, you'll most likely need to major in the particular subject you wish to teach (source).
No matter what level you teach at, you'll need to become licensed as long as you're going to be teaching in a public school. Private school teachers have their own rules. We're not sure, but we think they might be practicing witchcraft in there.