This example fetches the Webamp bundle from a free CDN, and fetches the audio file and skin from a free CDN as well, and loads Milkdrop visualizer.
You should be able to open this local html file in your browser and see Webamp working.
$ git clone git@github.com:captbaritone/webamp.git
$ cd webamp
$ open examples/minimalMilkdrop/index.html