So if I understand you correctly, you've uploaded a book file to pubit and then downloaded your file so you can check it over . . . right? And in reviewing your file, you did not see your cover that you uploaded to pubit for this books file . . . again, right?
If so, then that means you did not include a cover within your books file. The cover you upload will be melded with your book file for a reader when the book is actually purchased, not before. If you want an additional cover to show then it needs to be added to the front of your books file.
Once I open the book in Nook for PC, I see my cover. But when I first open Nook for PC, and look over the book I've downloaded, my book cover is a generic B&N cover. I uploaded the cover at PubIt! What else do I need to do....and how do I do it?
Ok, I need more information. Is this a copy you downloaded from your books edit page in pubit or did you purchase your own copy of your book?