Here you can see a list of all available newsletters. You can manage the items in the list using the appropriate icon on the left side - edit (), delete () and clone (). New newsletters can be created by using the New newsletter link.
If there is a large amount of displayed newsletters, you can filter them by their name using the filter above the list.
More resources can be found at Developer's Guide -> Modules -> Newsletters -> Overview.
Page url: http://devnet.kentico.com/docs/5_5r2/contexthelp/index.html?newsletter_list.htm