Script you can download, upload and search

Hello, I am looking to recreate something like this: http://gopetz.virtualave.net/adoption/index.html I need something which does exactly what that site does. How would I go about this please? The way I see it I think I'd need to break it down into parts and then put all those parts together? Which would be an upload part, a download part, a search part, a delete part...anything else? I'm very much a newbie to this so please try and make it nice and easy to understand Thank you!