You can use  Simple Java FTP Client  and add it as external jar for your project, you can also refer to this link
public class FileUpload
{
   /**
    * Upload a file to a FTP server. A FTP URL is generated with the
    * following syntax:
    * ftp://user:password@host:port/filePath;type=i.
    *
    * @param ftpServer , FTP server address (optional port ':portNumber').
    * @param user , Optional user name to login.
    * @param password , Optional password for user.
    * @param fileName , Destination file name on FTP server (with optional
    *            preceding relative path, e.g. "myDir/myFile.txt").
    * @param source , Source file to upload.
    * @throws MalformedURLException, IOException on error.
    */
   public void upload( String ftpServer, String user, String password,
         String fileName, File source ) throws MalformedURLException,
         IOException
   {
      if (ftpServer != null && fileName != null && source != null)
      {
         StringBuffer sb = new StringBuffer( "ftp://" );
         // check for authentication else assume its anonymous access.
         if (user != null && password != null)
         {
            sb.append( user );
            sb.append( ':' );
            sb.append( password );
            sb.append( '@' );
         }
         sb.append( ftpServer );
         sb.append( '/' );
         sb.append( fileName );
         /*
          * type ==> a=ASCII mode, i=image (binary) mode, d= file directory
          * listing
          */
         sb.append( ";type=i" );
         BufferedInputStream bis = null;
         BufferedOutputStream bos = null;
         try
         {
            URL url = new URL( sb.toString() );
            URLConnection urlc = url.openConnection();
            bos = new BufferedOutputStream( urlc.getOutputStream() );
            bis = new BufferedInputStream( new FileInputStream( source ) );
            int i;
            // read byte by byte until end of stream
            while ((i = bis.read()) != -1)
            {
               bos.write( i );
            }
         }
         finally
         {
            if (bis != null)
               try
               {
                  bis.close();
               }
               catch (IOException ioe)
               {
                  ioe.printStackTrace();
               }
            if (bos != null)
               try
               {
                  bos.close();
               }
               catch (IOException ioe)
               {
                  ioe.printStackTrace();
               }
         }
      }
      else
      {
         System.out.println( "Input not available." );
      }
   }
You can also use the Apache commons-net-ftp library, for more details you can focus on this link.
import org.apache.commons.net.ftp.FTPClient;
FTPClient ftpClient = new FTPClient();
try {
    ftpClient.connect(InetAddress.getByName(SERVER));
    ftpClient.login(USERNAME, PASSWORD);
    ftpClient.changeWorkingDirectory(PATH);
    if (ftpClient.getReplyString().contains("250")) {
        ftpClient.setFileType(org.apache.commons.net.ftp.FTP.BINARY_FILE_TYPE);
        BufferedInputStream buffIn = null;
        buffIn = new BufferedInputStream(new FileInputStream(FULL_PATH_TO_LOCAL_FILE));
        ftpClient.enterLocalPassiveMode();
        ProgressInputStream progressInput = new ProgressInputStream(buffIn, progressHandler);
        boolean result = ftpClient.storeFile(localAsset.getFileName(), progressInput);
        buffIn.close();
        ftpClient.logout();
        ftpClient.disconnect();
    }
} catch (SocketException e) {
    Log.e(SorensonApplication.TAG, e.getStackTrace().toString());
} catch (UnknownHostException e) {
    Log.e(SorensonApplication.TAG, e.getStackTrace().toString());
} catch (IOException e) {
    Log.e(SorensonApplication.TAG, e.getStackTrace().toString());
}