To rotate objects on the XY plane

1. Select one or more objects to rotate.
2. Click in the Utility Bar to enter Edit mode.
3. Place your cursor on one of the four Rotate gizmos.
4. Click and drag the cursor left or right to rotate the object(s).
5. Watch the angle readout and release the mouse button when the desired rotation angle is achieved.

   The objects you selected are rotated to a new orientation in the model.