Hi, it's not clear what you are trying to achieve here. Can you provide more details ? Or add a screenshot ?

I'll try to explain it more simply. I would like to put the module (or module position) in full artice image section (instead of image) in article viev (above content). But to do that I need to know which files I have to modify and this is what I'm trying to achieve here.

http://i.imgur.com/ImxYuXc.png

You can acheive this by using the loadmodule plugin :
https://docs.joomla.org/How_do_you_put_a_module_inside_an_article%3F/fr

Just place the tag {loadposition position[, style]} at the top of your article body and disable the image display.

I thought about it but I have 250 articles and It will be time-consuming...

You can also edit your template and add a module position just before the <jdoc:include type="component" />

Thank you for suggestions, but if I still would like to add module directly in full artice image section what file is responsible for this?

components/com_content/views/article/view.html.php ?

Yes.