If you have forgotten your password, you can easily reset it from the login page. Look for the Forgot Password link in the bottom-right.
At the following screen, simply enter the email address for your account, and click the Send me a link button.
You will, very shortly, receive an email with a unique, one-time-use link to reset your password. Click the Reset your password button in that email.
On the landing page, enter (and confirm) your new password. You can view password requirements here.
Click the Reset my password button to complete the process. You will be sent a second email confirming your password was reset.