Enroll in a Spanish dance class, which may be separated out into sections for children and adults. Classes such as those taught by Carmen de Vicente (See Reference 1) may involve footwork, beginning steps, and how to play castanets. You may also learn specific dances such as "Ole de la Curra," "Polo Gitano" and "Habanera."
Attend a flamenco festival. Check your local newspaper for advertisements or contact a dance company in your neighborhood. Although many festivals are held in Spain, you might able to find a local one. Flamenco festivals are where performers from the top levels of Spanish dance converge to show off their skills and new moves. Try to find someone to ask about lessons or serve as a mentor. There will also be vendors offering items such as flamenco clothing and shoes.
Purchase an introductory book such as "Flamenco Essentials: The Complete Beginner's Guide to Flamenco Dance, Music and Song" by Chris L. Wilson or "The Language of Spanish Dance: A Dictionary and Reference Manual" by Matteo Marcellus Vitucci, available online through booksellers such as Barnes and Noble, Borders and Amazon.
Watch flamenco and other Spanish dance videos online. Video sharing websites may have instructional videos teaching you step-by-step moves for free. You'll be able to practice in the privacy of your own home before going out and practicing on the dance floor.
Ask your local Spanish restaurants about theme nights; some bars and eateries will host Spanish music DJs and clear their floors after a certain hour, welcoming Spanish dancers of all experience levels. Some offer free lessons in the early parts of the evening before master dancers take over the floor.