Fedex
Go to Fedex Web Services and move to Development or to Production. Once complete, you will be shown a webpage containing your password and you will receive an email with the meter number and authentication key. Go into the admin under System -> Configuration -> Sales -> Shipping Methods -> Fedex and enter in your Fedex account number, meter number, key and password:
If you have development credentials, select Yes in Sandbox Mode.
To get access to the Fedex's address validation services, you will also need to be certified for Advanced Services without Label Certification. Call up Fedex, ask for Web Services department and ask to speak to an integration consultant. Tell the consultant you want to be certified for Advanced Services without Label Certification. They may take up to a day.