Count Red Cells

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

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

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