MARGIN UNIT OF MEASUREMENT CHANGES

I'VE BEEN USING EXCEL 97 FOR 7 YEARS. I'VE JUST GOT A NEW COMPUTER, AND I AM TRYING TO CHANGE THE MARGIN MESUREMENTS TO CENTIMETERS, INSTEAD OF INCHES. UNLIKE WORD, WHERE THERE IS A PLACE IN PAGE SET UP TO CHANGE UNITS OF MEASUREMENT FOR MARGINS, I CANNOT FIND ANYWHERE IN EXCEL TO DO THE SAME THING. I KNOW THIS CAN BE DONE, AS I SET THIS UP ON MY OLD COMPUTER. HOWEVER, THE BRAIN CELLS ARE DWINDELING AND I CANNOT REMEMBER HOW I DID IT.

HELP!!!!