How to model airplane in catia?
There are two ways. 1- Solid Modeling 2-Surfaces which can be done using Generative shape design and many other ways which i may not be aware of.
As Far as starting is concern, I always prefer starting with Nose cone, then fuselage, wings, tail and cockpit.
You can even start with Wings then follow up. Just be comfortable with what you start.
To proceed First have a blueprint of your desired aircraft.
Answered with a tutorial: https://grabcad.com/tutorials/how-to-model-airplane-in-catia
might help. This is my first tutorial. Feedback is valuable.