want to log into a shared folder on another server using a different user name and password.

I have an asp.net app written in c# and want to log into a shared folder on another server using a different user name and password.
How do I and can you give me some example code to allow me to connect to a shared folder on another server using a different user name and password.
Once connected, I wish to update a txt file
                    StreamWriter sw = File.AppendText(@\\flcy_fluency\DNC_Lists\TenantDNC.txt);
                    sw.WriteLine(tbTel1.Text);
                    sw.Close();
...