After installing and activating a new Sprout Apps sub menu will show named Help Scout Desk. Navigate to that page and enter your Help Scout API key and Mailbox ID.
Finding the API key
Finding the Mailbox ID
Shortcodes are used to display the support form, this shortcode can be added to any existing (or new) WordPress page.
By adding the Beacon code within settings will add a beacon to all front-facing sites. Pretty easy...and simple.
For a more advanced setup please review the Help Scout Desk full shortcodes documentation.