Hi Ray
Highlight the cell (or range of cells) where you want highlighting to occur
Format>Conditional Formatting>use dropdown to select Formula
is>=$D15<$F16>Format>Text (or Fill)>Green
If you have formatted a range of cells, then as the formula is relative, the
other cells would take the condition D16<F17 etc.
If you want all cells in the range to take the formatting based upon the one
condition, then make it absolute =$D$15<$F$16