Put the persons email address or nickname here that you wish to share a list with. If they are a Pro user of Out of Milk, they will receive an email that you have shared a list with them. They will now be able to see and modify this list.
or alternatively you can click Browse Friends to browse your existing list of friends and add them to the list.
To stop sharing a list with a friend:
Open the list.
Click Share List under the List Actions sidebar.
Click Remove next to the friend you would like to stop sharing the list with.