The Diamond theme comes with a little callout that is by default at the bottom of the page and looks something like the screenshot below:
Editing The Callout Globally
Like everything else in Diamond this is done via the WordPress Customizer under the “Callout” tab:
Editing The Callout Per Post/Page
You can also edit the Callout on a per post/page basis using the Page Settings below the post editor.
Adding widgets is simple. Browser to Appearance -> Widgets and drag and drop your widgets into your footer Columns. Or you can go to Appearance > Customize > Widgets and add widgets via the live editor (may be a bit slower on budget hosting plans).
Customizing The Footer
To customizer your footer such as the colors and columns go to Appearance -> Customize -> Footer.
By default Diamond includes a section at the very bottom of the site called the “Footer Bottom” area which you can use to add a copyright to the left and the “footer menu” to the right.