Is there an actuall api? or do you just mean what do i send to do a search?
I just searched for "blah", and the page sent this, u just need to know the form fields normally, and send the value of the needed ones for your specific search.http://www.google.com/search?hl=en&q=blah&btnG=Google+Search&meta=
alot of that could be broken away, to justhttp://www.google.com/search?q=blah
Hope I might have helped, if not well stick a D cone on my head, flip me upside down and call me an icecream.