You can find any tool by the Menu Structure HERE: https://turbocaddoc.atlassian.net/wiki/display/TC21UG/Menu+Structure

You can find the menu location of any tool by name HERE: https://turbocaddoc.atlassian.net/wiki/display/TC21UG/Tools+Mapped+to+Menus

Curves

Tools for drawing splines, Bezier curves, sketches, and revision clouds.

You can display the Curve toolbar by right-clicking in any toolbar area and selecting Curve