need a way to get excell to enter the "application user" name into cell c3 ?

Sub auto_open()
Sheets("log").Select
Rows("2:2").Select
Selection.Insert Shift:=xlDown
Range("A2").Select
ActiveCell.FormulaR1C1 = "=NOW()"
Range("B2").Select
ActiveCell.FormulaR1C1 = "=NOW()"
Range("A2").Select
Selection.NumberFormat = "dd-mmm-yy"
Range("B2").Select
Selection.NumberFormat = "h:mm"
Range("c2").Select

End Sub

thanks in advance