How do you use the brush tool in World Edit?

In WorldEdit, the brush tool allows you to modify terrain and structures quickly using your selected brush type. To use it, first select the brush type with the command /brush [shape] [size], where [shape] can be sphere, cylinder, etc., and [size] defines the brush's radius. Then, simply use the brush by clicking in the game world to apply the selected operation, such as adding or removing blocks. Make sure to have the appropriate permissions and a valid selection if required by the brush type.