Select
Activate select to make a selection of voxels that can be copy/pasted, moved, turned, or extruded.
Click and drag the mouse on voxels to define an initial selection. You can then further modify the selection box or use another tool.
Then you can extend a face of the selection by clicking and dragging an edge.
In addition, you can also move the selection by clicking and dragging a face.
The last way to modify which voxels are selected is by clicking and dragging a vertex over the voxels.
Move
Activate move selection to move the selection.
Move the selection in one direction by clicking an edge and moving the mouse.
Move the selection in two directions by clicking an face and moving the mouse.
Turn
Activate turn selection to rotate or flip the selection.
Click on an edge to rotate the selection.
Click on a face to flip the selection.
Extrude
Activate extrude selection to extrude a side of the selection.
Click and drag an edge to extrude a side of the selection.