I've heard that to transform (alien swarm sdk) to portal 2 sdk needs only a file called portal2.fgd
(said by a friend)

is that possible and from where can I get that fgd???
thanks for help

If you don;t have the fgd you have to verify your game through steam. You already said in another thread that you don't have portal 2 on steam thus not a legal version.

We won't help you with an illegal portal 2, locking this thread.
If you try it on a new thread again I will have to ban you. If you can't afford portal 2 wait for a steam sale and buy it cheaper or ask a friend.