Here's a pretty straightforward tutorial on how to widgetize footers.
I haven't used this myself. I only tweaked my footer to include ads and that was about it.
As far as your site goes, it's looking pretty good. Simple formatting regarding the navigation links, but it serves its purpose. You might consider making your chapter navigation links stand out more, either by increasing their size or making them bold, though that isn't really necessary. Your comments are neat and easy to read. Personally I'd have a divider between the actual story and comments, but that's just me.