Program to automate multiple ID (input)verification in URL

Question

A program to automate the process of checking a set of UserIds passing as a input to a webform in a url and get the status using webbrowser . for Single Ids its working , but to automate for N number of ids, loop is not working but taking the last id and returns the output.

private void button2_Click(object sender, EventArgs e)
{
string url = "https://www.verifyids.xhtml";
WebBrowser b = new WebBrowser();
b.ScriptErrorsSuppressed = true;
b.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(b_DocumentCompleted);
b.Navigate(url);
}
private void b_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
for (int i = 0; i <= 4; i++)
{
WebBrowser b = sender as WebBrowser;
b.Document.GetElementById("idnumber").InnerText = idarray[i]; //string
listobj = b.Document.GetElementsByTagName("select")[0].GetElementsByTagName("option")[1].SetAttribute("selected", "selected"); // string
response = b.DocumentText;
b.Document.GetElementById("frmType1").SetAttribute("value", "24Q");
HtmlElement btnlink = b.Document.GetElementById("clickGo1");
btnlink.InvokeMember("Click");
b.DocumentCompleted -= new WebBrowserDocumentCompletedEventHandler(b_DocumentCompleted);
b.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(b_result);
}
enter code here
}