For the basics of Calibre, why not view the introductory video on the Calibre website:
http://calibre-ebook.com/demo#tour
Plus here's a video from YouTube showing loading books onto the Kobo (Calibre is the first way it shows you):
How to load ebooks on the Kobo Touch e-Reader
I don't remember it being that difficult to set-up and use Calibre. Simply install it, the wizard runs and you tell it where you want it to store your books (Calibre stores any books you load into in it's own directory), and what ereader you have, and then it just works?
You click the Add Books button, tell it where the books are on your computer by browsing to find the files, select them and it'll load them into Calibre (if you have used ADE browse to the My Documents > My Digital Editions folder to locate them). When you connect your Kobo to your computer with Calibre running at the same time you can then just click the Send to Device button to load them onto your Kobo (though I prefer not to use Calibre and just browse for the files on my computer and drag and drop them onto my ereader).
Removing the DRM from the books is another step (and that info isn't allowed to be explained in detail on here, you need to search google for apprentice alf to learn how to do this).