Go to this site and use the code it gives there.
Click edit HTML and paste it in where you want it
http://services.google.com/searchcode2.html?accept=on
(Contributed by Martin)
http://martin.blow.googlepages.com
(Added by Hans)
http://hansdirkse.googlepages.com
also see the solution by Rami Mawas at http://rami.mawas.googlepages.com/gpctips#2