ok thanks

Well, then if that's the case, this guide will work for that as well.
Just because I used Day of Defeat: Source as an example doesn't mean that is the only Source game that you can do this with...
The file system for L4D should be very similar to DoD so just follow along and you should be good.

i'm pretty sure l4d2 is a source game

There is some Left4Dead stuff on the SFM workshop, but to be honest, I think most of it is in the Gmod workshop...

As for porting from the game, if it's not a Source Engine game then I have no clue how to rip those...

to sfm

can you make a tutorial on how you can port workshop content like workshop content from left 4 dead 2