Lead Developer
This thread explains how to get social icons in your navigation: http://generatepress.com/forums/topic/social-networks-buttons-on-nav-menu-bar/
The above plugin (thanks, Silvio!) is useful for showing icons in your widgets.
To show share buttons, there’s lots of options. This post goes over some of them: http://wpchronicles.com/best-wordpress-social-sharing-plugins/
Hope this helps 🙂