How do I start the free trial version of Excel 2007 after I have .
 

I registered for the free trial version of Excel 2007 for the home and
student. I have received the product key number but when I go to the home
page, I can not figure out where to go next to put the product key number in
and start the trial version. I have wasted hours going around in circles and
would appreciate any help.

Thanks