Attached Link: http://www.stansight.com/Freebie/bricks/

I'm trying to create a wall using the textures I found on a website (see link) but I don't know how to use the bump maps. (I've never really understood how to use bump maps.) There is a *.jpg and a corresponding *.png but I'm not sure how to use them together. Can anyone help? (I've gotten a far as applying the *.jpg to a cube but don't know what to do with the *.png)