If you've forgotten your password or are having trouble logging in to your Airbnb account, visit www.airbnb.com/forgot_password. Enter the email address you use for Airbnb and you'll be emailed a link to reset your password.
In order to change your password, you need to know your current password.
If you created an Airbnb account by connecting to Facebook, you were not required to create a password. You can continue to log in via Facebook. If you'd like to create an Airbnb password, first log out of your Airbnb account, then follow the steps as if you forgot your password. Once you create an Airbnb password, you'll no longer be able to sign in using Facebook, but your Airbnb account will still be connected to Facebook.