Could someone please advise me on what I do after I create a collection (and sub-collection) and then edit the pictures? Where can I find this folder structure and the edited pictures? How do I use them (e.g., to print, put in a Blurb book, etc.)?
You find the collection, and sub-collections, in Lightroom! Once you have organized your photos in Lightroom, you find this organization in Lightroom.
You want to print them? Print them from Lightroom's print module!
You want to put them in Blurb book? You do this from Lightroom's book module!
That's one of the major benefits of Lightroom ... it is a complete workflow system, from receiving the photos to "publishing" in the broad sense. It does it all for you. You don't need to know where the files are on your hard disk, nor do you need to export the photos, in order to make these things happen.
Now, if you need to use the photos in some non-Lightroom application (e.g. e-mail, web, commercial printer), then you could still export the photos and maintain the hierarchy you have selected, exporting a collection at a time to the desired folder. Yes, I know you said you don't want to do these things, I mention this for completeness.