If you once set up Facebook account on Windows Phone 7 device then you can access your Facebook information throughout your phone for example in the Pictures hub, People hub and the Me card. In following you may learn the process to set up Facebook account on Windows Phone 7 device.
Before starting the process this is important to know that your device should be connected to Wi-Fi or with cellular data service of your carrier. You should see the following guides how to use laptop internet on mobile, how to connect to WiFi on WP7 or continue to
Set up Facebook Account on Windows Phone 7
On “Start” screen tap on “Arrow”
Then tap “Settings” > “Email & accounts”
Tap “Add an account” > “Facebook”
Tap on “Email address” box and enter your email address which you have associated with your Facebook account, then tap on the “Password” box, and type your Facebook password
Tap “Sign in”
All is done. Now, your Facebook account is integrated to your Windows Phone 7 mobile phone.
Note: Users can only set up one Facebook account on their Windows phone 7 mobile phone at a time, so if they want to set up any other of Facebook account then first they have to delete the integrated one.