Instead all you need to do is point the built-in web browser at the upload website of your choice, and when you browse for a file on the WiiU you get given a choice of the main screen or the gamepad screen. Pick one, and the WiiU uploads a JPEG of it. Simples!
This leads me to today's Hyrule Warriors question, which who is this and where (if anywhere) is the person in the middle from:
The context suggests that it's Ganondorf, as this particular image shows up in several cutscenes referring to him. But the art style of the fairy-like chap in the middle is like nothing else in the game. It puts me in mind of the Zelda cartoons or possibly the manga.