Ok, i was tryng to make a mod, just that. But there were some problems, like my mod was pretended to be single player and co-op. As i see, portal 2 DONT support mods. So here all the ways i try to use:

Use the millenium tutorial
(it was a pretty tutorial, yes. But there some problems: NO co-op campaign, give up. And the when i edit the menu the things dont apply, because valve launch a update to they dont apply.)

http://www.moddb.com/mods/millennium/tu ... rtal-2-mod

Looking at a valve tutorial (a tutorial whit 5 steps, how easy?)

https://developer.valvesoftware.com/wik ... rtal_2_mod

asking a modders help
like using the update folder for new content and creating a new "dlc". It the best, but wont have a tutorial. I will try when i understand how he does(yes, he give permission).

i also asked lambda core, he give me these forums and a very useful suggestion: using the perceptual sixense folder. I will try, it seems easy on one way, except the fact it supposed to be "sixense".

I know 90% of portal 2 modders that make a portal 1 mod give up for making a portal 2 mod. But i wont give up. Really, if this is to be the future of science... (haha in just kidding, just want to make an amazing mod)

PS: sorry for my bad english. Yeah, that.