This theme has four widget areas. Three are for the top/bottom bars and one is for the page sidebar. Go to Appearance > Widgets and you’ll see them both.
This theme offers two different widgets, which are labeled with Krown [..] Widget. These widgets can be added anywhere in order to add some content to those areas.
For more advanced stuff (such as social icons or the twitter feed), please use shortcodes inside a text widget. Pasting any shortcode into a widget area will make that widget area to show the shortcode. Please see this article Themes Shortcodes to learn about shortcodes.