Help with multi-file downloader

I want to create a program that can go into a parent directory, travel to each folder in the directory and then download each file from each folder. I'd also like to make it so that I can control the number of folders it downloads at a time, e.g. if there's 100 folders, then be able to tell it to download folders 1-10, then at another point tell it to download folders 11-20.
This is the code that I have so far:

Code:

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        WebClient wc = new WebClient();

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            List<string> linkList = new List<string>();
            string url = textBox1.Text;
            string source = workerclass.getsource(url);
     

            int startindex = source.IndexOf("folder.gif");
            source = source.Substring(startindex, source.Length - startindex);
            while (source.IndexOf("<a href=") != -1)
            {
                startindex = source.IndexOf("<a href=") + 9;
                int endindex = source.IndexOf("/", startindex);
                string link = source.Substring(startindex, endindex - startindex);
                string fullink = url + link;
                linkList.Add(fullink);
                source = source.Replace("<a href=" + @"""" + link, "");
            }
            foreach (string link in linkList)
            {

                List<string> linkList2 = new List<string>();
                string newurl = textBox1.Text;
                string source2 = workerclass.getsource(newurl);


                int startindex2 = source.IndexOf("folder.gif");
                source2 = source2.Substring(startindex, source2.Length - startindex2);
                while (source2.IndexOf("<a href=") != -1)
                {
                    startindex2 = source2.IndexOf("<a href=") + 9;
                    int endindex2 = source2.IndexOf("/", startindex);
                    string link2 = source.Substring(startindex2, endindex2 - startindex);
                    string fullink2 = newurl + link2;
                    linkList2.Add(fullink2);
                    source2 = source2.Replace("<a href=" + @"""" + link2, "");
                }
                foreach (string link2 in linkList2)
                {

                    Uri reallink = new Uri(link2);
                    WebClient wc2 = new WebClient();
                    wc.DownloadFileAsync(reallink, link2+" file.zip");

                }
            }
           
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
    }
}

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Would this work to grab each file in each folder and download it? How would I tell it how many/which folders to download at one time as I previously mentioned?

You want to be able to download file 1-10 at the same time so your downloading all 10 at once?

This solution works across browsers, and does not trigger warnings. Rather than creating an iframe, here we creates a link for each file. This prevents mega warning messages from popping up.

Code:

---

/**
 * Download a list of files.
 * @author speedplane
 */
function download_files(files) {
  function download_next(i) {
    if (i >= files.length) {
      return;
    }
    var a = document.createElement('a');
    a.href = files[i].download;
    a.target = '_parent';
    // Use a.download if available, it prevents plugins from opening.
    if ('download' in a) {
      a.download = files[i].filename;
    }
    // Add a to the doc for click to work.
    (document.body || document.documentElement).appendChild(a);
    if (a.click) {
      a.click(); // The click method is supported by most browsers.
    } else {
      $(a).click(); // Backup using jquery
    }
    // Delete the temporary link.
    a.parentNode.removeChild(a);
    // Download the next file with a small timeout. The timeout is necessary
    // for IE, which will otherwise only download the first file.
    setTimeout(function() {
      download_next(i + 1);
    }, 500);
  }
  // Initiate the first download.
  download_next(0);
}
<script>
  // Here's a live example that downloads three test text files:
  function do_dl() {
    download_files([
      { download: "http://www.nt.az/reg.txt", filename: "regs.txt" },
      { download: "https://www.w3.org/TR/PNG/iso_8859-1.txt", filename: "standards.txt" },
      { download: "http://qiime.org/_static/Examples/File_Formats/Example_Mapping_File.txt", filename: "example.txt" },
    ]);
  };
</script>
<button onclick="do_dl();">Test downloading 3 text files.</button>

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