Use the Curves > New Curves > New CV Curve or Curves > New Curves > New Edit Point Curve tools to draw curves by clicking to place CVs or edit points.
To set what parameterization and degree the curves you draw will have, open the tool’s option box and set the Knot Spacing and Curve Degree options.
See Use the mouse and keyboard in tools.
For a degree 3 curve (default), the curve will only appear after 4 CVs have been placed.
Draw curves by placing edit points
See Use the mouse and keyboard in tools.