What you need to decide is when you want this code to run. For all pages, you can select "All Pages" as the scope. If you want to delay when this code runs until the DOM is ready, you can select "Dom Ready" as the scope, and if you want this code to run before any of the Tealium code runs, you should select "Pre Loader" as the scope.
All Pages is likely fine for the scope based on my guess.
Giving the added extension a recognizable title, you can publish the deployment out, go to your website, launch WebCompanion and see if the extension fired successfully. If you don't have WebCompanion installed, click on your email address at the top right of the TealiumIQ interface, click the WebCompanion menu item and follow the steps to install it.