Collection templates define how each item in your collection will be formatted and displayed. Setting up a collection template is very similar in regards to setting up content templates for an app or content layouts for a page.
Templates are created, edited, and deleted, within the Templates tab in the Collection Details window. To get to the window, first click Collection under Widgets in the My Apps menu.
Click details to the left of the collection.
Clicking the Templates tab will show a list of all the templates for that collection.