Hi friend, I hope with this links, you can made your helix, try to make the links and if you have some questions, just let us know,
Have a good day,
In Catia You Must To Make At first A Point For The Beggining Of The Helix
And a ligne
then Go To workshop Of Wirefrime And Surface Design And Search about The Helix Command And apply.
plz check helix picture...u can see this picture....helix pitch and dia...different every step