Some seriously bad advise given here (a few with good advise). Hire an Electrician and pay him to do the work or you could burn your house down and/or die. I've been an electrician for 25 years and have seen homeowners fu** up more wiring than you can imagine. We are currently rewiring a house that burned because they doubled/tripled up circuits on oversized breakers. Wire size determines breaker size. Why risk your families safety getting advise from cigar smokers or off the internet.
Do your own plumbing get wet, do your own electrical you can die.
If your breaker box is a Federal Pacific or Zinsco GET IT CHANGED NOW, google Federal Pacific or Zinsco breaker to see what I mean. This should run $1500-2500.
http://www.inspectapedia.com/fpe/fpepanel.htm
http://www.inspectapedia.com/electric/Zinsco.htm