VB.Net ขอความช่วยเหลือการส่งค่าจาก Textbox ที่มีโค้ด html ไปอีก textbox ให้เลือกแต่ลิงค์ Url รูปภาพ

public static string getHTML(this string url)
        {
            string html = "";
            try
            {
                System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(url.Trim());
                System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
                System.IO.StreamReader sr = new System.IO.StreamReader(response.GetResponseStream());
                html = sr.ReadToEnd();
                sr.Close();
                response.Close();
            }
            catch { }
            return html;
        }

string strRegex = @"""(https://.*?\.[pngj]{1,})""";
Regex myRegex = new Regex(strRegex, RegexOptions.None);
string strTargetString = @"";

foreach (Match myMatch in myRegex.Matches(strTargetString))
{
textbox2.Text+= "\n" + myMatch .Group[1].Value;
}