flying entity mod with mount

Hello, a few weeks ago I started with MCreator
so I'm a beginner
 

I was making a mod with a flying entity that spawns,
can be tamed and can be ridden on (think dragon maybe)
 

I manage to do all of the above but when I mount myself on the entity
I can only move in the x axis (walk forward, backward and to the sides)
but I cannot go up or down to fly
 

Does anyone know how to add the controls
or what I can do to get the entity to fly?

Thank you very much for taking the time to read and help me :)