How to save a file on local drive in windows form application

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C#

.NET

WinForms

I have an Excel file named "sample.xlx" in my Project Folder named "File Folder".I have a button named "btnDownload".When the user click this button the above excel file should be saved on local drive.The path of the file should be dynamic so that when the project is deployed on other PC then the path should not break.Note the application is offline that means the saving of file don't require internet connectivity.
How to solve this problem?

What I have tried:

private void btnDownload_Click(object sender, EventArgs e)
{
SaveFileDialog sfd = new SaveFileDialog();
sfd.Filter= "Excel file |*.xls;*.xlsx";
if(sfd.ShowDialog()==DialogResult.OK)
{
Stream fileStream = sfd.OpenFile();
StreamWriter sw = new StreamWriter(fileStream);
sw.Write("jhdfhsefefdhk");
sw.Close();
fileStream.Close();
}
}