Alt attribute

Hi, I've decided to use images for the dice that we use since the forum I have is an RP forum. I was wondering if there's a way to add an alt tag for the few occasions when someone is having issues viewing the images? In the admin panel it has a field to put in the URL but doesn't directly let you change any of the html and was curious if there might be a way to do this?

Thanks in advance for your time on this. You guys are awesome and fairly patient and I appreciate it.