Go to your local library and look up books relating to space, planets and the solar system in the reference section. To make the task easier, speak to a librarian to point you specifically in the direction of books about Neptune.
Log onto the Internet and research Neptune on the National Aeronautics and Space Administration (NASA) website. There are several pages dedicated to Neptune, including an overview, moons, rings and facts and figures. Review this material to learn more from an authoritative organization.
Head to a bookshop and find a textbook, study guide or fact-book about Neptune. Flick through physics study aids or science books to educate yourself about Neptune.
Perform a generic search through an online search engine and find websites that provide educational material relating to Neptune. For example, KidsAstronomy.com, NinePlanets or UniverseToday have pages dedicated to facts and figures about Neptune.
Read and review all the information you have gathered. Repeat this several times until you feel confident in your understanding of the icy planet. Find out how scientists believe it was born, its history and current climate.
Learn the information by reading extensively, and tell your friends and family different facts so that you can remember them without looking at your books. Encourage them to ask questions so that you learn the information thoroughly.