To paste the schematic, go to Y coordinate 12 (flat world) to paste. This is because there is redstone under the cannon and if pasted above or below the ground the redstone will fall and break. This won't break the cannon, but there will be less power.
The cannon will always face north.
The cannon is a sniper
The cannon launches 4 TNT at a time.
How to add to schems:
To add to your schematics, do this for windows: Go to file:
Windows C:/Users/*your user*/AppData/Roaming/.minecraft/config/worldedit/schematics
Remember to replace *your user* with your user (example: Alex)
Put the schematic in that folder.