Toolbar : 
PartEditor : Geometry toolbar 


Menu : 
PartEditor : Add menu > Geometry submenu> > Add Spline 

What to do : 
Note: Add Spline is the only sketchelement (other than Add Point) in which you do NOT drag your mousepointer.
The Spline sketchelement is now in the graphicarea. 

An open and closed Spline. 
Notes:
To show the splinehandles, click the Spline.
To hide the splinehandles (default), click the Spline again. 

To edit its geometric properties: 

Edit the Node's Position Use the PartEditor:
Use the Point Display and Properties dialogbox
Edit the Spline's Angle at the Node
Edit the Spline's Curvature at the Node
