Excel VisualBasic Script

Sub FormatContainsA()
    With Selection
        .FormatConditions.Delete
        .FormatConditions.Add Type:=xlTextString, String:="A", _
            TextOperator:=xlContains
        ' other choices: xlBeginsWith, xlDoesNotContain, xlEndsWith
        .FormatConditions(1).Interior.Color = RGB(255, 0, 0)
    End With
End Sub