[DllImport("wininet.dll", EntryPoint = "FtpPutFile")]

    public static extern bool FtpPutFile(

        if (!FtpPutFile(ftpHandle, file.SourceFileName, file.DesctinationFileName, (uint)file.TransferType, 0))

static extern bool FtpPutFile(IntPtr hConnect, string lpszLocalFile, string lpszNewRemoteFile, int dwFlags, IntPtr dwContext);

Declare Function FtpPutFile Lib "wininet.dll" Alias "FtpPutFileA" (ByVal hFtpSession As IntPtr, ByVal lpszLocalFile As String, ByVal lpszRemoteFile As String, ByVal dwFlags As Integer, ByVal dwContext As Integer) As Boolean

Direct Link: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wininet/wininet/ftpputfile.asp