im doing a project about process analysis and jig design for the skin of an aircraft (one panel only, not the hole skin)
This is basicly the the same way as described by Carl but maybe it gives a better visual on how and where the curve on the surface is placed.
Answered with a tutorial: https://grabcad.com/tutorials/how-to-draw-on-a-curved-surface-on-catia--1
Another way is to place points on the surface you want to make a curve on and then using the spline command to make a curve and using the surface as support.
Answered with a tutorial: https://grabcad.com/tutorials/how-to-draw-on-a-curved-surface-on-catia--2
1. Drafting => Text - Enter your text.
2. Save your text as a dxf or dwg. (not quite sure what format, try them bouth)
3. enter in GSD (generative shape design), build your surface
4. In a different sketch insert your dxf or dwg (copy/paste)
5. project it on your surface
I dont remeber the command exactly but you can wrap your text on the surface.
For more details, please search on Youtube the bottel of Coke tutorial, I think that you will find it more explicit
Hope it helps :)