Is there any site or channel making a guide to making for working with the Portal 2 Editor or making mods for portal 2? IT seems not much has been 'officially' documented on the portal 2 editor.

SkiwittGaming has pretty nice tutorials for complete beginners on their Youtube channel. They taught me quite a lot. It's not official, but it's good enough for science.

Pretty much everything I needed to know was here - http://developer.valvesoftware.com/wiki ... vel_Design