WorldEdit

Selections:
//wand
While holding the tool, left click will select point 1, right click will select point 2.

//desel
Removes your current region selection.

//hpos1
//hpos2
Selects the block you're looking at as the 1st or 2nd selection

//pos1
//pos1
Sets 1st or 2nd selection based on where you're standing

//chunk
Selects the entire chunk you're in from bedrock to sky

After making a selection:
Once you've made a cube selection with the wand, you can use:

//cut
Removes all blocks within selected region.

//set <block>
Sets the entire selection to x block.

//walls <block>
Will set the outside border to x block.

//replace <1> <2>
Replaces one block <1> with the other <2>. (Set block 2 to 0 [air] if you want to remove that specific block.)


Other useful commands:

//undo
Will revert last command done with WorldEdit. (Spamming //undo will result in most, if not all of your work being undone.)

//redo
Will redo the last command you //undo'd with worldedit.

//hycl <block> <height> <radius>
Will create a hollow cylinder, the center will be where you're standing.

//cyl <block> <height> <radius>
Same as above, just not hollow.

//hpyramid <block> <size>
Creates a hollow pyramid, with center where you're standing.

//hsphere <block> <radius>
Creates a hollow sphere where you're standing.

//sphere <block> <radius>
Same as above, just not hollow.

//drain <radius>
Will drain all liquids within x radius.

//fixlava <radius>
Will smooth out lava pools.

//fixwater <radius>
Same as above, except with water.

//green <radius>
Sets all dirt to green grass within the radius. (Note: sometimes will not work for every block. You may have to place a few by hand.)

//copy
Copies all blocks in current worldedit selection

//paste
Will paste last selection copied in a different position.