install a widget

Not understanding your question. Are you referring to a specific widget? Are you looking for a widget to display a button for people to Digg your site? Do you want a widget that displays the sites that you Digg?

Copy at Digg, then paste into your theme’s individual post page if you get that code from Digg. OR, if you just want to digg-it button, paste it into a widget text field OR, if you aren’t using widgets, paste into your theme’s sidebar.