Sadly apps cannot be side loaded. They are purchased from the B&N store (on device or online) and will automatically download and install without any need to interact.
Of course this applies to non-rooted NC's. Not sure if sideloading becomes available in that situation.
I am expecting delivery of a Nook Color this Friday and would like to know if apps such as EzPDFReader can be side loaded or do I have to download it using the NC? If so, what is the proceedure for loading it on the nook?
Since sideloading is a multi step process, really it's so much easier just to turn the wifi on and download the app directly anyway. It only takes a few seconds to download most any app. And EzPDF reader is an available app from the nook app store.
So to download it - turn on your wifi - go to shop and browse the apps. click the one you want and there will be a purchase button. then you will be asked to confirm the purchase. then the button will turn to download. That's the entire process.