Click Site in the navigation bar, then select Customize Design in the section bar. Choose what area of your site you want to add the social icons to, such as Entire Site or Homepage.
Drag the Social Icons content block to where you want it to appear.
You can choose which accounts you want to show in the Social Icons settings, which can be found by hovering over the content block and clicking the wrench icon.
Select the social accounts you want to show by turning them On. Be sure to scroll through the list to see them all.
When you enable a social icon, a field will open for you to type in the URL link to that social media account.