5.Download this and this. You need to put the scenes.image file in the scenes folder, and the sound.cache into the sound folder.
Copypaste the "TeenGirl", "Biker", "Manager" (and "Namvet once we get Bill working) folders in
(C:\Program Files\Steam\steamapps\common\left 4 dead\left4dead\scenes) into the Left 4 Dead 2 scenes folder
(C:\Program Files\Steam\steamapps\common\left 4 dead 2\left4dead2\scenes), and then you need to do the same for the sound.
(C:\Program Files\Steam\steamapps\common\left 4 dead\left4dead\sound\player\survivor\voice\) and
(C:\Program Files\Steam\steamapps\common\left 4 dead 2\left4dead2\sound\player\survivor\voice\)