A shot in the arm muscle of a small volume of vaccine fluid (1/2 of a milliliter) at 0, 2, and 6 months. You want to get the vaccine on board ideally BEFORE you ever become sexually active for the most protection, but even if you have had sex, or even if you have had HPV, you should still get the vaccine (it will protect you against the types you don't already have).
If you are late for getting the second or third shots you should still come back and take them later. You are likely to achieve excellent protection as long as all 3 shots are taken within a year. You should try to adhere to the 0, 2, and 6 month schedule for the best results.
GARDASIL is a registered trademark of Merck & Co., Inc.