Is this what you are looking for?
Edit: Sorry about the previous short answer...I was having connection issues. There are other tabs at that location including
which may help.
If you lose the link, you can find it by going to https://developers.arcgis.com/ and finding AppStudio under the Configurable Apps... list. Then at the bottom of that page (or that is were I found it) is "Learn" link that takes you to the first link I listed above. Not your typically location for help, so good to remember the developers page.
You could eventually get there from http://www.arcgis.com/features/apps/index.html but you would again have to do a bit of clicking.