Wait, eeeeeeerrrrrt! : )
What are you talking about? Install software? Please explain, I think you may have asked the wrong question to find out what you were trying to do. The "file manager" that you asked about is just a place to see all the files and folders inside a domain (user uploaded files, directory structure of the domain (httpdocs, etc)). It sounds like you want to do something else. Please explain so we can try to help you out.
Thanks!
Craig