When you select Products, two boxes are displayed. "Products assigned to page" (the top box) has a list of products that are currently assigned to the selected page. "Products not assigned" (the box below) has a list of all available products. You can filter the results in the "Products not assigned" box by using the search interface at the bottom of the screen to search for the products you want to assign to your page. Click the List All Products to remove the filter and display all available products again.

Select products from the list that you would like to appear on the page and click Add to move them from the "Products not assigned" box to the "Products assigned to page" box.

Remove unwanted products from the "Products assigned to page" box by selecting them and clicking Delete. You can also click Remove All Items to remove everything from the "Products assigned to this page" box.

When you have finished managing the products on the page, click Save Changes to return to the main Pages screen or click Arrange Items to adjust the order in which the products will appear on the page. Click Assign Items to go back a step so that you can choose to assign a different item type to the page.