Cannon Battle controls

Use the [Arrow Keys] to maneuver the Chopper.
Hover over the HQ (center of the circular Command Center) and hit [Space] to dock.

While docked at the Base, click [Left Mouse] on the Structures in your Base to select them.
Use the [Arrow Keys] to aim weapons.
Use [Left Ctrl] to fire weapons.

Select the HQ and hit [Left Ctrl] to relaunch Chopper.

Hover over a freestanding Structure and hit [Space] to airlift the Structure.
Hit [Space] over suitable terrain to deploy the Structure.

Airlift an Outpost (the Structure to the left of the Command Center) to an unoccupied Energy Well to create a new Base.