Board.KolibriOS.org

Alright, so I have setup Kolibri to run on VirtualBox(if anyone needs help doing this, i'd be glad to help you. I know they have virtual box for Ubuntu users, not sure if that includes all Debian based distros though)
I'm a beginner when it comes to translating operating systems, so i'll need a step-by-step process of where to begin. Should I attempt to edit from within Kolibri or a linux distro/windows 7? I'm not actually sure where to start. Any help would be appreciated, thanks.

You can review this thread for a start, and ask questions if you have after you've read it: viewtopic.php?f=23&t=1867
You can edit from anywhere you want, just KolibriOS doesn't have SVN client right now, so you will have to commit the changes from another OS (Linux/Windows).

I've downloaded the FASM compiler for windows 7, but I am not sure about which svn client to use for windows in order to download the source code, any suggestions?

You can use TortoiseSVN for example, although you can use any client you want.