>> I've seen the free movie : Basic Fire Ring tutorial (https://www.simplymaya.com/movie_pag...mhtml?tut_id=42)
>> And I've done all the tutorial say and at the final render, I don't see a "real" fire but a blue fire ...


Thats a fairly good tutorial !

I say "fairly good" because:
1. They ought to have wrote a script to read.
2. They should have used a capturer that allows editing the mouse movements and used an "outliner pen".

At least it was "correct" and easy to follow.

I'll attach a Maya Binary of the result and the video (in .gif format) that you end up with:

EDIT BY RAGECGI: NOTE for 8.5 users, - This is for Maya 2008, just fyi