TCAdmin comes with the game configuration file which enables the game to be installed and ran by TCAdmin, but it does not ship with or provide the game files.
If the company you leased your server from cannot provide them, you'll end up having to upload the full COD4 installation to your server via the means of FTP. And yes, i mean the entire 7GB it installs.
You should upload them to C:\GameInstalls\COD4 by default, if you ran the wizard and pressed the "Create Directory" button with the default location.
As soon as TCAdmin detects files in the relevent GameInstall folder, it will allow you to install it by clicking on "Create a Game and Voice Server" inside the admin login of your TCAdmin panel.
This Knowledgebase article from TCAdmin may help:
And this will almost certainly help if you want to run Steam Based games with the panel:
If in doubt, your best to contact TCAdmin support.