How to upload file to FTP server using C#

Add below namespaces,

using System.Net;
using System.IO;

Create a button and add the below code under button click

        string filename = "c:\\test.txt";
        string ftpServerIP = "<IP address>";
        string ftpUserID = "<userid>";
        string ftpPassword = "<Password>";

        FileInfo fileInf = new FileInfo(filename);

     string uri = "ftp://" + ftpServerIP + "/" + fileInf.Name;

        FtpWebRequest reqFTP;

        // Create FtpWebRequest object
        reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + ftpServerIP + "/" + fileInf.Name));

        //Provide ftp userid and password
        reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);

        // By default KeepAlive is true, where the control connection is not closed
        // after a command is executed.
        reqFTP.KeepAlive = false;

        //Specify the command to be executed. Here we use upload file command
        reqFTP.Method = WebRequestMethods.Ftp.UploadFile;

        //data transfer type we use here is binary
        reqFTP.UseBinary = true;

        // Notify the server about the size of the uploaded file
        reqFTP.ContentLength = fileInf.Length;

        // The buffer size is set to 2kb
        int buffLength = 2048;

        byte[] buff = new byte[buffLength];

        int contentLen;

        // Opens a file stream (System.IO.FileStream) to read the file to be uploaded
        FileStream fs = fileInf.OpenRead();

        try
        {

            // Stream to which the file to be upload is written
            Stream strm = reqFTP.GetRequestStream();

            // Read from the file stream 2kb at a time
            contentLen = fs.Read(buff, 0, buffLength);

            // Till Stream content ends
            while (contentLen != 0)
            {

                // Write Content from the file stream to the FTP Upload Stream
                strm.Write(buff, 0, contentLen);
                contentLen = fs.Read(buff, 0, buffLength);
            }

            // Close the file stream and the Request Stream
            strm.Close();
            fs.Close();
        }
        catch (Exception ex)
        {
            string ErrMsg = ex.Message;
        }

Execute the code and check the FTP server for the file.