The SMC Minecraft server uses the Residence plugin for establishing homes. This gives you the power to claim a plot of land and protect it from mobs and unauthorized players. Please note that claiming land as a Residence costs $$$, so be sure to check out the economy guide for info on how to make $$$.
I recommend this tutorial for those who want a visual walkthrough.
To begin, start by crafting a Wooden Hoe. This is the selection wand used to plot out your residence. Then, use the wooden hoe to select any two opposite corners by left-clicking on a block for Position 1 and right-clicking a block for Position 2. This works in three dimensions, e.g. you can select the northwest corner of the floor and the southeast corner of the ceiling to select the entire area.
You can modify your selection using commands. The commands always affect the selection you are currently standing inside, and will always use the direction you are facing.
/res select expand <number> will expand the selection by the specified number of blocks. Conversely, /res select contract <number> will contract the selection instead.
Once your selection is to your liking, you can use the command /res select cost to see how much it will cost. If you'd like to purchase it, you can use the command /res create <residence> to claim it. Doing so will deduct the appropriate amount of $$$ from your Vault balance.
Be careful not to mix up the commands /res select expand and /res expand. The first modifies your selection. The second modifies your residence directly, and will deduct the $$$ from your vault. The same goes for /res select contract and /res contract.
Once your residence is claimed, you can customize it to your liking.
By default, most actions such as interacting with containers, breaking blocks, and placing blocks are protected. This means that players other than the residence owner cannot perform these actions. If you would like to set a specific flag to true or false, you can do so using the command /res set <flagname> <true|false|remove>. You can also use the command /res flags to bring up the Residence GUI, and set flags from there.
If you want to set flags for a specific player, use the command /res pset <residence> <player>. This is helpful for sharing residences with another player. You can also use the command /res padd <residence> <player> as a shorthand for setting a handful of the more common flags to True for that player.
/res tp <residence>/res remove <residence> will free up one of your three slots. However, you do not get your $$$ back once spent./res area add <residence> <areaID> to further customize individual areas of your residence.