General :: Does Versions Control System Work On Server Or Per Website

I tried hard so that I can stay away from version control but in almost good job specifications, I find version control as requirement. So I thought I had to start from somewhere. I always tried to read it but haven't got much luck with it. So I have few problems to ask. I am confused and I really want to know how can I use version control in my context and how will my working environment change with it.

I have Linux VPS Server. I use capnel/whm to create sites in php/joomla. So is version control a software or script which I can install on my linux box like ./configure. Or I have to install it on every site like any framework I use Dreamweaver to edit files via FTP. Now if I install version control then do I still use same method to edit files or then method gets chnaged What about the database like MySQL will it stays same or its also version controlled Will version control make my system slow and how much space it uses on my server.