Envoy:
I can well understand that this is a lot of information to swallow in one time. I meant to give it to you in smaller daily doses for about a week or so, but fate chose otherwise.
If you get stuck somewhere (also in the "aha" experience) feel free to ask.
extra question: ok, but that turban...that material does not have pores, now does it?
No. You can also use other methods to add the effect. One is to open another file, apply grain to it,then depending on the size of what you want enlarge to, say 250% and use prtscr to paste it in yet another file in PS, take a square or so and make that seamless tile. Then save as a pattern.
Go back to your original with turban, open a new layer and apply, indeed: that pattern.
That's why the size of the grain (enlargement) is so important.
The rest is etcetera.