How to upload your app, one take
This is a Lynda.com training video, and is most likely everything you will need to know to upload your apps to the Mac Store. The cost for this knowledge is apparently not free, but it is well produced and comprehensive.
How to upload your app, another take
Speaker "T-shirt" Booth shows you very clearly how to upload your game to the Mac App Store. Booth's series of videos is terrific if you're interested in designing and writing games. The games he creates are simple and fun, and I recommend giving them a look.
The following video is near the end of his series and will show you how to upload your app through Mac Desktop Publishing.