This sample shows the required steps to apply B-spline curves to fit data.
Select data series on left panel [Points].
Select menu item
The 'Approximation line' Wizard appears.
On step 2 select item 'B-Spline'.
On step 3 set 'Control points' value 'M=50'.
Select item 'Closed curve' checked.
New graph appears. See how curve fit conforms your data.
On step 5 select line color and click