@Skorpi58
Thank you for your respond. I had bad times but finally I managed to unlock my bootloader and install TWRP. Before I started, I was absolutelly beginner and I didn't even know what is bootloader. Plus that, english is not my primary language. But now I am starting to understand everything.
Now I have some questions before install of the KangVip ROM:
1) Is root needed for instalation of KangVip ROM? I unlocked bootloader without rooting.
2) I did full backup (ticked all checkboxes) with TWRP of my current system to SD card. Is the backup a snapshot* of my current system/settings?
*) snapshot within meaning that I will be able to restore my system/settings/apps(data) from the backup to the same state as it was before installing ROM? In case I will not be satisfied with the ROM ...
Thanks a lot and sorry for lame questions