Granting access to lists is simple, and need only be done once.

1. Go to Account and click on Manage Users.
2. Select the user that will need access to the list, and in the Action column, click on the Edit link.
3. On this page, the List Access dropdown box shows the lists this user could access. The lists this user can access are highlighted. To grant access to a list, and only one list, simply click the list name. To grant access to multiple lists, hold the Ctrl key down while clicking the desired list names. All lists the user has access to will be highlighted.
   
4. Click Save Changes and you're done.