Hooray! It works.
I’m going to leave this post so that you can comment on whether or not it works for you. If not, please leave a comment for me and in it specify what browser you are using. Thanks.
Update: Many thanks to Mike Neel who pointed out in the comments that the images I had uploaded were too large for most monitor resolutions. I’ve modified the original image and uploaded the other two so that all should now display more normally for most people viewing the site. (Note: For those of you viewing this post mirrored on the Knoxbloggers site, you can only see the effect of the lightbox script if you view this post on my blog.)