To install unzip and drop it into your ~/Library/Widgets folder. Open Dashboard, click + and you should see it in your widgets. Drag it to open it and click the i to set your Sitellite info.

The info to set is the Sitellite URL, username, password, and defaults for access level and status. Click Done to save, then you can drag files onto it and they will be added to your Web Files.

In the future I'd like to add it so you can drag multiple files or a whole folder at once, and to make the 'uploaded' text go away after a few seconds.