Facebook connect is an API built into facebook and invision power board versions 3.x+ allowing users to link their forum username and facebook username. In the current version, members will be able to update their avatar, profile picture, status updates and "about me" pages and synchronize them with info from their facebook. Take note that synchronization takes place every 24 hours (subject to change) so updates will not be immediate.
Setting Up:
In order to use facebook connect, follow the procedures below.
1. Log in to your SG.COM account, and go to your Member Settings (aka My Settings).
2. Click on the Profile tab and find "Manage Facebook Connect". Click on it.
3. Click the "Connect with Facebook" button. If you are logged in, you should see a pop up window similar to the one below. Otherwise, a pop up will appear asking you to log in.

4. Once you are logged in, facebook will ask you to allow the application API to connect to SG.COM. You will see the screen as shown below. Simply click "Connect".

5. After this, your SG.COM account will now be linked with your facebook account. You now have the option of choosing what you wish to synchronize with your SG.COM account. See the picture below.

6. You're done! If you ever wish to unlink your SG.COM and facebook profile, click on the "Disassociate Account Now".
If you have any questions, feel free to ask.

PS. Note that once you have connected your account to facebook, you will be able to log in to SG.COM simply by being connected to facebook!