How to Link Steam to Facebook
With the Steam service, users can purchase and download games, then play them with friends around the world. If you use both Steam and Facebook, it is possible to link your accounts. Linking accounts lets you see Facebook friends that also use Steam, so you can add them to your list of fellow gamers. To connect your Facebook and Steam accounts, you only need to log in to your Steam profile.
Go to the Steam website and click on "Community" at the top of the page.
Type your Steam username and password into the boxes. Click "Login."
Click on "Edit my profile," located on the right side of the page.
Scroll to the bottom of the page and click "Facebook." Your Facebook and Steam accounts are now linked.