You will utilize the overloaded Save method of the Workbook class providing the FileFormatType.Pdf enum member that converts the native excel file to pdf format.
The above steps are implemented in the following example
//Instantiate the Workbook object
Workbook workbook = new Workbook();
//Open an excel file
//Save the document in Pdf format
'Instantiate the Workbook object
Dim workbook As Workbook = New Workbook()
'Open an excel file
'Save the document in Pdf format
More about Aspose.Cells for .NET
Aspose.Cells is a .NET component for spreadsheet reporting without using Microsoft Excel. It supports robust formula calculation engine, pivot tables, VBA, workbook encryption, named ranges, spreadsheet formatting, drawing objects like images, OLE objects and importing or creating charts. You can also create Excel file using designer spreadsheet, smart marker or API and apply formulae and functions. It supports CSV, SpreadsheetML, PDF and all file formats from Excel 97 to Excel 2007.