Usage:
Start ArmA 2, in main menu press ALT-E.
First you need to create "center", then create group and only then you will be able to create units.
Rotating objects; Hold shift = left click on object and drag. CTRL = elevation. Alt = Up and Down.
Selected Object:
Hold left mouse to move object
Hold ALT (Move Up/Down)
Hold Shift (Rotate Unit)
CTRL-C to copy selected, CTRL-V to paste.
View:
Move camera up and down: Middle mouse scroll or Q and Z
Move camera: Hold right mouse button or WASD
Slow down camera movement speed: Hold CTRL + WASD
Control like FPS at current level: HOLD Right mouse button + WASD
When rotating your object it will snap to the closest surface.
Check out this BIS topic and skip directly to Ohara's comments where he mentions:
Please note that this is NOT a real time editor, the mission pauses when you do edits, so this is purely 3D editor only.we expect that we will "open" it by some patch, its there, but need some tweeking