To get a collection into your service, it must be included in a view that is published in your service. A simple solution is to add the collection to your start page.
Go to Content and select content structure
Find the Startpage or the view you want to add the collection to
Type the name of your collection in the selection field or find your new collection in the dropdown
Select it and click “Add selected item”
Move the collection to the wanted position on the page with drag and drop
Click on save