The Falkreath Stormcloak Camp is one of eleven Stormcloak Camps set up to fight the Civil War. This one is located just down the hill to the south-east from Orphan Rock.
Thorygg Sun-Killer, camp commander, will inform about the ongoing Stormcloak efforts. A Quartermaster sells weapons, apparel, and misc items (also buying all those).
In the camp, the Dragonborn can find the following amenities: