(15.09.2014 13:15)Valery Wrote:  

Spoiler (Click to View)

Any attempt to change explorer rights is prohibited.

OMG what are you doing?! RMB on Explorer.exe, then Run as admin (the option with a shield icon). File rights are not equal to process rights.

(15.09.2014 13:15)Valery Wrote:  Beside I have no the slightest idea why this idiot system is showing me 4 users and how to switch between them.

Because they aren't users. If you look a bit more closely, you will see a caption. It says they are user groups.

(15.09.2014 13:15)Valery Wrote:  And how to not install things in C? How to create for example D drive? I have no idea of such things...

Spliting a drive into partitions (logical drives) is done before installing anything (including OS) onto it. Usually OS installers contain all necessary tools and specifically ask you this berofe installation. Blame whatever you bought your computer from.
Additionally you can try Acronis Disk Director. It allows to redistribute partitions on existing drive, but may take insanely long time (up to 12 hours) or fail (if your drive is too full).