You can edit the content that appears below your logo in your website's footer using the "Footer" content settings found under Website > Site settings > Footer in your NationBuilder Control Panel.
The links in the Wayfinding and Take Action columns are controlled via page tags. Any page tagged with "wayfinding" will appear in the Wayfinding column, and any page tagged with "take action" will appear in the Take Action column. The links will always appear in the order that they were published (so you adjust the order they appear by adjusting the publish date).
The facebook and twitter links in the Connect column are automatically populated with links to the facebook and twitter accounts of your website's primary broadcaster.