Begin by perusing some of the basic knowledge of black holes.
http://amazing-space.stsci.edu/resources/explorations/blackholes/
http://www.damtp.cam.ac.uk/user/gr/public/bh_home.html
http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html
Black holes include a lot of complicated concepts that are not generally
covered in introductory physics classes. If you find material that you know
in your gut is beyond the level of our class, then please skip ahead! We
know enough to still explore and appreciate the basic elements of black
holes. Search for things you understand, or think of new questions to ask!
http://science.howstuffworks.com/black-hole.htm
This site is phenomenal - and includes videos rendering an artist's
interpretation of what black holes "look" like.
http://www.nasa.gov/audience/forstudents/9-12/features/F_Black_Hole_Extreme_Exploration.html
Finally, all of that imagination and information is all very well and good,
but what proof is there for black holes, and where are they? Check out these
Hubble Space Telescope photos showing places where NASA thinks black holes
are likely to be. They're awesome!
http://hubblesite.org/newscenter/newsdesk/archive/releases/category/exotic/black%20hole/
I know I already said finally, but check out this short article about the
Relativistic Heavy Ion Collider in New York. At this particle accelerator
they do experiments that are so fast, hot, supercharged, and cutting edge
that scientists can simulate what the Big Bang might have been like, or how
black holes actually work. Also, see what Stephen Hawking has to say about
black holes.
http://news.bbc.co.uk/2/hi/science/nature/4357613.stm
http://news.bbc.co.uk/2/hi/science/nature/3913145.stm