In the 'Compose' view, you will see that your List of items tile is empty (unless you are coming back to edit it!). To populate the List of items tile, you will need to drag items of content from the content chooser on the left of the compose view, into the tile. To then edit the properties of the tile, hover over the tile until you see the blue 'Edit' button in the top left, and then click on it.
There are nine fields in the List of items tile edit interface:
This defines how many items the tile will show, useful if you want to have a scrollable list.