This only works if your server supports SSI, if it doesn't ask you server-admins to activate it. You just have to add the following HTML-Code where you want the DownloadCount to be displayed:
The script will then display the HTML-Code specified using the General-Admin-Script (Introduction, like "this picture has already been shown", then the SC for this picture, then the 2nd part of the HTML-Code (like " times.").
On some servers (especially on NT-Servers) you have to use a different SSI-call to include a script. Try it if include virtual doesn't work:
Please note that most servers only parse files with the extension ".php" for SSI-calls. If your server does not parse the SSI-calls, try renaming the file where you want to include the scripts to ".php" or contact your administrator to change the configuration of the server.