[Plugin: NextGEN Gallery] Add an [x] instead of click to close?

Hey, I’m making a site for a client, and he said he wanted an X in the corner of single images because it doesn’t explicitly say how to close the image and continue browsing the site.

How would I go about editing this and adding a (x)close text to a corner?

Thanks in advance,
Rich

http://wordpress.org/extend/plugins/nextgen-gallery/