Should I put it in PTW\extras ,where is medieval Japan,and is there an official scenario for this new units or should I find it in scenarios forum?

If you mean the extra WWII units, yes. But if you have the PTW/Extras directory, it probably means you have PTW in which case you downloaded them for nothing as they were in PTW (they are for the people who have Conquests but no PTW).

Scenario : no official scenario for Europe with all the units but plenty are used in the WWII Pacific conquest.

I have c3c 1.00. (and ptw as well). I didn't found anything like world war II. I saw many scenarios suppose that this folder is already installed,but I thought that there is official scenario about this,like for Shogun (in c3c)... but it seems not