I have a photo library on my hard drive, I imported those files into lightroom, or I thought I did...The photos show up under my Mac Hard Drive drop down with in Lightroom.
Do I edit the photos from right there. ( selecting a photo from that Hard Drive collection and go to develop?) Will the changes I made to those individual photos, be saved to a copy of the photo in this Hard drive library?
Yes, so far you're doing well. It doesn't matter where in Lightroom you are, a collection or the main view ("All Photographs"). Click on a photo in the Library Module, press D (or click on the word Develop) and begin editing. Your edits are always stored in the catalog itself, automatically, without you having to actually tell Lightroom to do the save. Changes are not saved to the file itself, by default. Any time you want to see your edited photo from then on, just open Lightroom, find the photo, and your edits will be displayed. If you need a copy of the edited photo for use outside of Lightroom (web, e-mail, print, etc.) you would use the menu command File->Export to create a new file with the edits.
Please view tutorials or free e-books for beginners on Lightroom.
First of all, Lightroom DOES NOT save the changes to the images. Your master images that are imported into Lightroom are left untouched. All of your adjustments are stored in a catalog. The catalog is a database file on your computer. It contains information about your images, where they are located, and all the adjustments you have made to those images. However, it does not contain the image files. They image files are located in folders on your computer, and you can designate where those folders are located as you import your images.
A collection is something that you create to group images together for one purpose or another. It could be an event, a trip, a family, a wedding or what ever. You decide what you want in a collection. You can make adjustments are either in the collection or in the folder, you are working on the same image. A collection is something that only exists within the catalog.
If you want a copy of the image to give to someone that includes all of your adjustments that you have made using Lightroom you would use the export function to export a copy of that image.
Since you are new to Lightroom, I suggest that you take the time to watch this set of introductory videos. They were designed for Lightroom 5, but everything that is discussed would apply to other versions as well.