次の Excel VB コードを C# に書き直すのを手伝ってくれませんか?
Range("C9:E11").Select
Selection.FormatConditions.Add Type:=xlCellValue, Operator:=xlEqual, _
Formula1:="=1"
Selection.FormatConditions(Selection.FormatConditions.Count).SetFirstPriority
With Selection.FormatConditions(1).Interior
.PatternColorIndex = xlAutomatic
.Color = 255
.TintAndShade = 0
End With
Selection.FormatConditions(1).StopIfTrue = False