StreamWriter on hosting not working??????

hello i am using stream writer
and i saved the file on my local pc using this code

Using sw As StreamWriter = New StreamWriter("C:\Myfolder\" & weeknumber & ".xls")
                    Using hw As HtmlTextWriter = New HtmlTextWriter(sw)
                        gvToExcelSheet.RenderControl(hw)
                    End Using
                End Using


I want to publish my code on ftp  even if someone has a folder on c:\Myfolder nothing happen
i need help to modify the streamwrited in case i am using hosting server
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