When you drag your QuickPics Instagram Stack out, you will see the above stack appear on your page.
There are no contents within the stack itself that you need to edit. You need to publish this page to see it, you can not preview this page in Rapidweaver.
You do not need to eneter your Instagram information in the stack settings, after you publish you need to click on the link to finish the setup by entering your instagram login information and granting acces to instagram from the QuickPics Instagram stack (watch the overview video below for more on this if you are confused).
Choose your number of images, the size, the theme (gallery or slideshow) and many other settings such as image style and caption settings in the stacks settings.
For an summary of the remaining settings please refer to the QuickPics Instagram Settings section.