Darling - Social Sharing Icons Setup
This theme uses the Jetpack plugin, which can be obtained here or by searching in
Dashboard > Plugins > Add New.
Once installed and activated, sync this with your WordPress.com account. If you do not have an account there, you will need to create a free account.
Navigate to Jetpack > Settings > Engagement and click on the arrow to the right of Sharing to begin editing the settings. Verify that the settings match the screenshot below.