How can we transfer files from one machine to other machine?

See more:

C#

FTP

I have a task to be done transfer of files from one machine to other machine using C#.So I have seen many links and articles to transfer files from one machine to other machine.I want to know if we want to transfer files do we need to have the Windows Identity ? or any login credentials .

My Code

if (!Directory.Exists(destinationFolder))
        Directory.CreateDirectory(destinationFolder + "\\" + DateTime.Now.ToString("ddMMyyyy"));
    string[] files = Directory.GetFiles(sourceFolder);
    foreach (string file in files)
    {
        string name = Path.GetFileName(file);
        string dest = Path.Combine(destinationFolder, name );
        File.Copy(file, dest);
    }
    string[] folders = Directory.GetDirectories(sourceFolder);
    foreach (string folder in folders)
    {
        string name = Path.GetFileName(folder);
        string dest = Path.Combine(destinationFolder, name);
        CopyFolder(folder, dest);
    }

Can any one tell me the pros and cons of transfer of files using C# over LAN?

When I am copying the files it is saying "Logon failure: unknown user name or bad password."

How can we handle this login to the windows account?