Count Red Cells

Function CountRed(rRange As Range) As Long
Dim rCell As Range
For Each rCell In rRange.Cells
If rCell.Interior.ColorIndex = 3 Then CountRed = CountRed + 1
Next rCell
End Function

Here is a more useful version that can be used with various colors (Use the color index for InteriorColor)

Function CountColor(rRange As Range, btInteriorColor As Byte) As Long
Dim rCell As Range
For Each rCell In rRange.Cells
If rCell.Interior.ColorIndex = btInteriorColor Then CountColor = CountColor + 1
Next rCell
End Function