You can open up your self-service portal (knowledge base and forums) to your Facebook fans via the Facebook page tab in your integrated Facebook pages. The support page tab is a view of your support portal served inside Facebook through an iframe. It contains the default header from your self-service portal with the navigation bar. In addition, users will be shown their recent ticket history, a list of recent solution articles and popular topics in your community forums.

For more information visit - https://support.freshdesk.com/support/solutions/articles/126729-creating-a-branded-support-tab-on-your-facebook-page