STEP ONE
Find yourself a place to make your homestead! Please refer to the rules regarding where bases are able to be placed.
STEP TWO
Even as a solo player, you will need to make a group to be able to have a territory. To do so, open your map and look at the top of the screen and select 'Group'. From there you can make your group name and shortname. STEP THREE
Now you'll need to craft a flag pole kit. This will require 3 short sticks and one rope. Combine them together and you should get a prompt, though, make sure it says 'flag pole kit' as there are other options with this recipe.
STEP FOUR
Place your flag! Flags are auto build. Please refrain from merging flags into static objects (ie. buildings, trees, vehicles) as this can render the inventory glitched and you will not be able to interact with it properly.
To dismantle a flag, use these items in this order: Hatchet, shovel/pickaxe, then sledgehammer.