how to crete excel in landscape and convert it in pdf

please, I need help.

I was able to generate an excel file and convert it to PDF. But I print it in portrait gold I would like the printed landscape. here is the problem code. Microsoft.Office.Interop.Excel.Worksheet = XlPageOrientation.xlLandscape();

(Microsoft.Office.Interop.Excel._Worksheet)(ExceltoPdf(this.textBoxAccountNumber.Text, this.textBoxAccountNumber.Text).ActiveSheet).PageSetup.Orientation =Microsoft.Office.Interop.Excel.XlPageOrientation.xlLandscape;