Go to: http://www.ferc.gov/docs-filing/efiling.asp
Click on the eRegister button.
Then follow these simple steps, which also appear on FERC's website.
Register as a FERC Online User to obtain a FERC I.D. and password (you will need to do this even if you have an eFiling account). FERC Online will then send you an email confirming your registration.
Go to your email program's Inbox and open the message from FERC Online. Click on the link to validate your account.
Once you are a registered FERC Online User, log in to FERC Online by entering your registered email address/FERC I.D. and your password.