When you remember your Facebook password, you can use the account setting to change it. When you forgot your Facebook password and can't get in, you can read this page http://lnkd.in/tWC2qu from a SmartKey website.
If you're logged in to your account: Click the account menu (down arrow) at the top right of any Facebook page. In the drop down menu that appears, select Account Settings. Scroll down to Password, click the change link, and follow the instructions.