1. Enter the distance of the concentric or parallel entity from the original entity in the options tool bar shown at the top.
2. Enter the number of parallel or concentric entities to create in the options tool bar.
3. Click the base entity. The parallel or concentric entities are created on that side on which the mouse cursor is located while selecting the entity.

QCAD Professional:

Additional options for the handling of polylines are shown in the options tool bar:

Mode

• Polyline Mode: In this mode, the offset tool offsets entire polylines and other contours at once.
  If multiple polylines or contours are selected, they are all offset together as shown here:
  
• Segment Mode: In this mode, individual segments of polylines can be offset.