Sorry i didn't see your PM.
Ok i'll use screenshots here.
To find your avp2 directory open up my computer
And go to the drive where you installed avp2.
I installed it in data. or F drive.
Go into the drive and locate your aliens vs predator 2 folder.
Ok now your inside. Go to your CUSTOM folder.
If one doesn't exist, make one. (Right click and create new folder)
Your CUSTOM folder is where all your Rez files will be contained.
Skins, new models, sometimes maps.
When you download a skin you will get a window like this.(select open when you download and then "i agree")
When you get the window with the files in, simply highlight the REZ file. And click extract.
Find the directory of your avp2 CUSTOM folder and click extract.
Once it's done open up avp2.
Don't click play just yet.
Open up the OPTIONS.
and enter -rez custom/rezname.rez
Replace rez name with whatever the file name is called.
For instance for my wolf skin you would enter:
Once you've entered it make sure that the box saying:
"always specifiy these command-line perimiters"
Make sure the box is crossed. Click ok and then play.
I recommend testing a skin works by going into the online host section. And looking at the character classes.