Minecraft Factions: Claiming Land

I've been trying to fully understand this for a while now, and I've found it so hard to find a proper answer. I recently started watching a few lets plays on YouTube of Factions, and I decided that I'd like to try it out. A couple of my friends gave me their kits and I'm really keen to make my base and start moving forward. The problem is, I do not understand what /f claim does. How does it automatically know what land to claim? Does it claim a default radius? Someone explain it to me before my brain explodes. In the gameplay, it looks asif it automatically knows which land to claim. I don't understand it… Anyway, let me know in detail if anyone would like to help! Don't give me the usual answer like, "It claims the land you're standing on" or "It claims the chunk". I'd like to know how much land it claims and where to claim it from and what you require to claim and WHAT IT DOES. If there are any external commands please let me know what those are also.