You can click the Sign up/Login button and the login screen will appear. You need to click the Forgot Password button. The screen shown below is the screen that appears when you click that button.

You can enter the User name (ie., the User id which you gave while registering)  and click the Change Password button.  Once you do it, a password reset link will be sent to your mail id.  You can change your password through the link provided in your mail.