Spanish can be learned at most universities and high schools; furthermore, numerous online language courses exist. Though online classes are often a poor substitute for having someone actually speak the language with you, they are a cheap and valuable resource for brushing up on Spanish vocabulary, grammar and punctuation.
Depending on your region, classes put together by the local government, a religious institution or a public school might be available. Often times, these classes charge a fee, though it is not as high as taking a class at a university. Public classes are more common in areas with large Spanish-speaking populations.