how to add dynamic rules based on user input to webconfig using XmlNode

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C#

ASP.NET

WebConfig

I want to add a rule, the location path and allow roles determined based on user input .. example TextBox1 to provide location path and textbox 2 to provide a rule for the user.
I want the results in a web config as below:

<location path="Report/Default.aspx">
		<system.web>
			<authorization>
				<allow roles="USER"/>
			</authorization>
		</system.web>
	</location>

so far my c # code like this:
but I am confused to apply as I want :

protected void AddRoleRule(string location, string selectedrole)
  {
      Configuration config = WebConfigurationManager.OpenWebConfiguration(Server.MapPath("~/Web.config"));
      XmlDocument xDoc = new XmlDocument();
      xDoc.Load(config.FilePath);
      //if the rule exists update the rule
          //create location element and the path attribute with it's value set to the
          //selected page
          XmlElement newLocationelement = xDoc.CreateElement("location");
          XmlAttribute newLocationAttrib = xDoc.CreateAttribute("path");
          newLocationAttrib.Value = TextBox1.Text;
          newLocationelement.Attributes.Append(newLocationAttrib);
          XmlElement newSystemWebelement = xDoc.CreateElement("system.web");
          XmlElement newAuthorizationelement = xDoc.CreateElement("authorization");
          //create the allow element
          XmlElement newAllowelement = xDoc.CreateElement("allow");
          XmlAttribute newAllowAttrib = xDoc.CreateAttribute("roles");

          newAllowelement.Attributes.Append(newAllowAttrib);
          //create the deny element
          XmlElement newDenyelement = xDoc.CreateElement("deny");
          XmlAttribute newUsersAttrib = xDoc.CreateAttribute("users");
          newUsersAttrib.Value = "*";
          newDenyelement.Attributes.Append(newUsersAttrib);
          newAuthorizationelement.AppendChild(newAllowelement);
          newAuthorizationelement.AppendChild(newDenyelement);
          newLocationelement.AppendChild(newSystemWebelement);
          newSystemWebelement.AppendChild(newAuthorizationelement);
          xDoc.DocumentElement.AppendChild(newLocationelement);
          xDoc.PreserveWhitespace = true;
          //write to web.config file using xml writer
          XmlTextWriter xwriter = new XmlTextWriter(config.FilePath, null);

              xDoc.WriteTo(xwriter);
              xwriter.Close();

      }

thanks in advance