Adding your widget
From MediaWiki Widgets
Initially new widgets get added to the "ProtoWidget" namespace to make sure new widgets go through a security check before they get published. As soon as this check is done the widget will be moved to the regular "Widget" namespace. Go ahead, create a Widget page - once one of reviewers looks at it and approves it, it will appear in the Sample Result section on the description page.
Note that you will need a user account on this wiki to be able to do this.