You need to install a custom Targa plugin first (which will allow you to save your file with the alpha channels - in the standard targa format you can't check the 'Alpha Channels' checkbox in the save options because it is greyed out). You can download this plugin from my webspace: click.
/edit: Btw, you asked it before: http://www.srcds.com/forums/showthread.php?tid=673. If that explanation isn't clear enough just ask
.
/edit: Btw, you asked it before: http://www.srcds.com/forums/showthread.php?tid=673. If that explanation isn't clear enough just ask

May the Source be with you...
Want to know which ports to forward on your router for a Source DS? Click here!
Want to know which ports to forward on your router for a Source DS? Click here!