If you want to use Fastdownload, you need to mirror every file that has to be downloaded to the client on a webspace (this files should be Bziped compressed), and on the gameserver (not Bziped compressed) as well.

To enable Fastdownload you need to add this into your server.cfg

sv_downloadurl "YourWebspaceUrl/cssdownloads"

Then upload your files to the gameserver. Now log in to your webspace via FTP.

Create a folder named "cssdownloads" (without "") and in this folder you create the subfolders maps, materials, sound, etc.

Now you need to bzip all your files for your webspace.

If you're using Windows as your OS at Home (Server hasn't to be windows), use the BZIP Compression Batch , simply Drag & Drop some files on the batch file (not to much files on the same time, every time about 5 files max), if you're using Linux, find some Package Tool that can compress files into the Bzip Format or use the console commands.

Now, after all your files have the .bz2 Extension, upload them to your webspace, restart your server and your server should now use the webspace for downloads.