Your account username is the email address you entered during registration. If you have forgotten your password, click the "forgot password" option under the login button on the home page.
After you have clicked on "Forgot Password" a pop-up box will appear requesting that you type your email address. Type in your email address and then select "Reset Password".
An email with a password reset link will be sent to your email address. Click on the link immediately as the link has a time limit. You will receive a temporary password. When you login using that password the site will require you to change your password. Enter the temporary password in the old password field, and the password you plan to use in the future in the new password field.