So many topics to cover in so little of time! Time dilation, spacetime continuums, all the sorts of fun stuff you learn in upper-level cosmology courses. Alas, we can't do justice to Einstein's theories or results here, but we can take a sure enough stab at it. The book I keep referring to is Einstein, His Life and Universe by Walter Isaacson. It's really a great read and I don't want to sound like I'm just telling you to buy a book just for the sake of buying it. If you want to learn about relativity, but are too intimidated by Einstein's own book that he wrote on the subject, Isaacson covers it in depth as well as more than you ever bargained for.
A New Hope is by John Williams