My client recieved a call from a user that stated when then came to the product list page - and next to the text Add: the text box is filled with "0"

They assumed the were out of stock. While this is an internet user issue - I would like to address this. My client would like the "0" removed from the box.

I think a statement and the beginning of the page to explain how to add quantities would address the issue.

What page am I editing to add this statement?