Though some information has been highlighted in the links below, you should still take the time to explore it's pages and links. Through correspondence or online courses, you can earn an Associate's Degree, a Bachelor's Degree, a Master's degree or a Doctorate in several different areas. Be sure to investigate this. The education is invaluable and the Army will help pay for it. Just as you can continue your civilian education through correspondence, so can you continue you military education, as well.
Many military schools offer correspondence courses as well.
Visit this page to familiarize yourself with what the Army offers. Another central repository of information for the soldier that wants to further his or her education. This site is restricted to members only, but then, membership is free.