Have you looked under the Help menu?
Please clarify you question...
Do you know how to get to the Welcome Screen once you are in the Premiere Elements 12 Editor?
Do you want to know how to reset the Welcome Screen so that it launches to Elements Organizer 12 or the Premiere Elements 12 Editor?
Then it is Premiere Elements 12 Expert or Quick workspace, Help Menu/Welcome Screen as already said
Please let us know if you found what you sought.
Thanks. The Help menu resets the Welcome screen.