Here is a great demonstration of one theory of gravity and how it warps space-time.
A great book that explains this theory well, at least it did for me, is The Fourth Dimension by Rudy Rucker. He has another book titled The Fourth Dimension: Toward a Geometry of Higher Reality that cover the topic as well.
He often cites a class science fiction book Flat Land by Edwin Abbott Abbott that is a must read as well. (Free on Kindle)