There are several resources for interested sighted people who want to learn braille.
If you just want to see what the basic letters and numbers are, visit the American Foundation for the Blind's Braille Bug website. http://www.afb.org/braillebug/
If you want a more intensive series of lessons that will teach you all of the symbols, contractions and special rules, take a look at the Shodor Foundation's Braille Through Remote Learning website. http://brl.org
If you have a close family member who is blind, you can take a correspondence course from the Hadley School for the Blind. http://hadley.edu
If, after these introductions, you decided that you want to become a certified braille transcriber, you may go through the certification program offered by the Library of Congress http://www.loc.gov/nls/bds/courses/index.html