When working on a page or page template inside the editor screen, you will find all of the available widgets on the right-hand side of the screen in the widget "toolbox." You can add any of these widgets to the page by simply dragging and dropping the desired widget into place.
Widgets are easy to use and all share common operations. Once you get the hang of working with a widget or two, you will find it easy to acclimate to working with any of them.