The thing you downloaded is just a plugin/behavior template, to give you a quick guide/starting files to make either a plugin and/or a behavior.
If you want to make a plugin, be sure to only unzip the "Plugin template" folder into your "exporters/html5/plugins" folder. Else go for the "behavior template" in the "behaviors" folder.
If you now launch C2, you should be able, in the "Insert object" dialog, to see a "plugin template" object that you can add to your project.
As it is though, this plugin won't do much.
You need to open the .js files in a notepad and edit them to add the relevant code.
That's where the SDK manual (the link in Ashley's post) really comes in handy.
I hope this helps you getting started.