I can't find any entry in the NPC editor I see beard , eyes , eyebrows , everything but this...

Also how can I do to make an Old man?

Some races have face textures that make them look older ... some do not. I'm pretty sure Nord Race has these textures

Scars - I have never found a way in the CK (though I think you can do it in game), I don't know why

(Obviously, you could make your own textures, but that's just way, way to advanced for me!)

The head parts subsection contains the various scars for all races. Tatoos are under the skin tone; you have to choose a color.

The oldest you can make an NPC look is about 50; for older, you'll have to make them an elder by race.