First, choose a "master password". Make it hard to guess. It could be a password that you already use, or a new one -- or even a long pass phrase -- but do make sure that you remember it.
To generate new passwords, choose an easy-to-remember parameter, like the name of the website that you're creating a password for. Hashapass will then generate a password based on your master password and the parameter. The passwords are never transmitted to our server.
When you need that password again, just enter the same master password and parameter. The generated password will be the same every time. Given the same master password and parameter, Hashapass will always give you the same result.