Private Sub CommandButton1_Click()
Sheets("année").Select
Dim c As Date
c = Sheets("année").Rows(1).Find(what:=Range("a2").Value, LookIn:=xlValues)
Dim x As Range
Set x = Sheets("année").Range("b1:q1").Find(c, , xlValues, xlWhole, , , False)
ActiveSheet.Range(ActiveSheet.Cells(4, x.Column), ActiveSheet.Cells(8, x.Column)).FormulaR1C1 = "H"
End Sub