How to protect your buildings:
a) Mark an area up to 30 blocks by 30 blocks (20×20 looks usually better, though). It’s easiest if you simply build a big square or rectangle.
b) Take a wooden stick out of your inventory.
c) Left-click on the corner closest to you. (Let’s say this is the left front corner of your plot.)
That’s the normal click. You should get the response “PLACED PRIMARY SELECTION POINT…..”
d) Right-click on the corner where you want your plot to end. (This will be the right back corner of your plot. Remember: Your plot should only be up to 30 x 30 blocks! If it’s bigger, we’ll remove the building.)
That’s the other click, using the mouse button to the right of the mouse wheel. You should get the response “PLACED SECONDARY SELECTION POINT…..”
e) Type /res select vert
In words: Forward slash (no space) res (space) vert
This will select all the blocks from bedrock to sky limit.
This step is very important! Otherwise people can still build on top of the height of your wall. And you don’t want that.
f) Type /res create name (whatever you want to name it, for example /res create MineTower)
The name must not have a space, “Mine Tower” would not work, “MineTower” is fine.
Done! Your plot is now protected, and you can start building!