With Apex underway the Arma 3 Units page and system now allows users to join numerous units. This allows members of a unit to display the units emblem in game.
Sign up to Task Force Raven Fires units page here
In order to be able to take full advantage of this functionality you must create a Bohemia Interactive account and then use that to join the TFRF unit. After you have created your BI account you can then link your Steam profile.
You can create a Bohemia Interactive account here
Once you have done this you can enable the unit in game.