We use the Factions plugin to manage player groups and land claims but it is not configured in a typical Faction server way!
For a full list of commands and features, you can check out the official Factions guide but below are the basics to get you started.
It’s all about power
With factions you need power to claim land, 1 unit per chunk (16×16 area). You will earn 2 power units per 1 hour played and you will lose 2 power units per death so be careful! Each player can earn a maximum of 100 power units, more than enough for any personal build. If you want to claim something bigger you will need to team up with other players. A Faction with 4 players can claim 400 blocks.
/f create name creates a new faction
/f money deposit x will put money into your faction bank, you need this for claims
/f claim o will claim the chunk you are standing in, check the dynmap to see your claim
/f unclaim o will unclaim the chunk you are standing in
/f sethome will set a spawn point for your members, they can use /f home to get there
/f invite add playername will invite a player to your faction, they have to use /f join factionname to join
/f promote playername will promote the player within your faction. There is a follower, member, officer and leader rank.
The above commands will get you started. On the official guide page you will find many more commands that will enable you to deal with members, set flags for mobs, permissions etc. Before asking staff always check the guide, its very detailed.