Widgetkit has a simple and easy to use interface. When you open Widgetkit you'll get an overview of all available widgets. Using the navigation bar you can click through them to open the individual settings of a widget. In general Widgetkit provides two types of widgets.
Content type widgets like slideshows, accordions etc. help you to organize your content in a slick way. You can include them using shortcodes in your article or through modules and widgets everywhere on your page - even multiple times on the same page.
The Widgetkit Manager gives you a list of all your widgets and related actions like edit, copy and delete.
These type of widgets like the lightbox or mediaplayer are globally available and can be used on any page. Simply use their HTML markup or attributes to activate them in any article or any custom HTML module and Text widget. The widget settings define a selector on which elements the widget should become active. It comes preset with a default selector which works for all common use cases, but you are also able to change it if you need to.