Modifying the Gallery Shortcode

I really don’t know PHP at all, and aside from being able to take the border off in the media.php file for the Gallery shortcode, I can’t figure out how to customize it further — and I don’t even know if this is the solution to my problem.

I have a pretty straightforward mainbar/sidebar setup. I frequently run galleries underneath my posts by inserting individual thumbnails, and when readers click on them it takes them straight to the full-sized image file in the uploads directory.

What I’d like to do is set it up so clicking on the thumbnail takes the reader to the full-sized image, just more or less in a child post the way the Gallery shortcode would if it didn’t default to medium images. But I want to be able to do this while keeping the layout of the thumbnail galleries I use now, which the shortcode doesn’t seem to allow me to do — especially if I want rows with different numbers of columns for horizontal and vertical thumbs. (Here’s an example of what it looks like: http://dailyfiasco.com/2009/11/16/caliendo-starts-decade-run/)

I really don’t know what the solution is here — Scraping together something in CSS? Will it require javascript? I spent most of the day trying out plugins and couldn’t find something that was suitable.