read some stuff about einstein's general theory of relativity to see how gravity is interpreted in macro terms.
(the combining of the 3 spacial dimensions we know and one dimension of time to get a "fabric" of space time- think of a bowling ball, ie planet, on a stretched out bedsheet)
quantum gravity is very tricky on the other hand. i think string theory has some interesting theories about gravity, (ie gravitons, closed loop strings which may be able to leave our three dimensions and enter a third dimension) but im really no expert. im sure someone with more of a quantum physics bckgd can give a better insight about gravity.
if you like this stuff but not all the technical jargon, id recommend picking up some books by dr michio (sp) kaku. he has a great mind for explaining these things to non physics majors.
also, this website, actually a pbs documentary about string theory that you can watch streaming, talks about gravity a bit, and it is broken into a number of small chapters.
http://www.pbs.org/wgbh/nova/elegant/program_d.html
-light