How to make such navigation

Hello.
I am a beginner and I have a problem.
There is a structure of the site
DOC1
DOC2
DOC3
...
DOCn
And i have a subfolders in this structure.
In index page I want to see only:
DOC1
DOC2
DOC3
...
DOCn

but in DOC1 or DOCn folder
DOC1
SUBDOC1
SUBDOC2
SUBDOCn
DOC2
DOC3
...
DOCn
How can I do so?

And the next question.
I would place the folder DOC1 at subdomen DOC1.domen.com and other folders respectively.
This is possible?

Regarding the first part, just use wayfinder with the &hideSubMenus parameter active, it will automatically output the structure you are needing:

&hideSubMenus
default: FALSE
values: [ TRUE | FALSE ]
description: The hideSubMenus parameter will remove all non-active submenus from the Wayfinder output if set to TRUE. This parameter only works if multiple levels are being displayed.

Check out all the parameters for wayfinder here:
http://www.muddydogpaws.com/development/wayfinder/parameters.html

Regarding the second question, I am not sure but I don’t think that will work natively.

Thank you for U Answer.
Im founded this plugin http://modxcms.com/Subsites-Subdomains-825.html and this http://modxcms.com/forums/index.php/topic,2059.90.html
But nothing work ((
Pls help