Excel 2000 (or a later version if necessary)

I know generally how to do conditional formatting, e.g., with the
compaison of the cell value with an explict (hard coded) number or
string. But how does one make the comparison between the value of the
current cell, and, e.g., the value of the cell immediately above it.
Any attempt I make to put a range address as the test value bombs.

Is there some element of code I'm missing, or does conditional
formatting not do it at all.

TIA.

Fred Holmes