If you have social media pages for your department/project, you can include links to these pages that will show up in the footer of your site. To add them, navigate to the Theme Settings link from your Site Builder dashboard (admin/dashboard, under "Other Administration").
Check the box called "Include Social Media Links in Footer". Then, check the appropriate boxes for the various social media options. You will need to provide the requested information for Twitter, Facebook, Instagram, YouTube, etc. Some social media options require a full URL, while for others you can just enter the username.