To distribute a published article via email firstly you have to enable the Distribution module and you'll need to have Admin level access. You can find the Distribution module in Modules tab of Admin/Settings screen:

Go to the main menu and click on Articles/List Articles, find the published article you want to distribute, go to Distribution tab, and check "Enable" checkbox.

Once Distribution for this article is enabled, you can add Distribution Methods. You don't have to select Email Template or enter