As far as we know, there are no black holes anywhere near the Earth, so they effect us so little as to nothing. In fact, nobody has actually seen a black hole, physicists are just pretty certain they must exist because of their calculations of what must happen when particularly large stars collapse. Black holes are incredible dense collections of matter - so dense that light cannot even escape. A black hole with the mass of our sun would only be ~1 km across (0.6 miles). So, if a black holes were near us, we would be gravitational attracted to it (however, don't be worried).
Here's a web page where you can read about falling into a black hole:
http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html