Tonma (./1) :
After for the fix file itself. (Rom S). I tried YY-CHR but without success. I tried with ngtools_011 but no access to palettes (for the fix editor).
I can see the tiles using the plugin NeoFixFormat after a decode8. But the pallets are not good when I load the pallets P Rom. There is something I musn't do.

decode8/recode8 is known to not have accurate results.
The NeoFixFormat plugin should be able to load a game's .s1 and .FIX files without any sort of conversion...
Palettes will need to be manually entered (and then saved via Palette -> Save RGB Palette). Right clicking on an entry in the palette brings up the editor; I recommend changing from R8G8B8 to R5G5B5, which gives you a mostly-close approximation for Neo-Geo colors (however, no dark bit/RGB-1 support).

Tonma (./1) :
Does anybody have a specific tutorial to NG?

I started by taking a sample fix ROM from one of the games (or the SFIX from the BIOS), copied it, and edited the copy. Sadly I don't have a full tutorial.

Tonma (./1) :
And for the fix rom tiles, you can not import picture, we must do everything by hand?

I don't really have a straightforward answer for this, though YY-CHR is able to accept clipboard data (with a 256 color palette).