Multithreading Webrequests To Update A RichTextBox Form Control

This probably shouldn't be too hard for someone to answer...even though I've spent 2 days trying to get it right. ::sigh::

I have a RichTextBox1 on my form. I need it to update every half second pulling HTML off of my webpage. I USED to have it update every half second with timers but everything keeps getting clogged and I realized I have to multi-thread.

My code so far is

Imports System.Threading
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

[Code]....

(This is an example of code from the bigger project) So I guess my question is how do I send out about 10 of these threads (Will the sleep suffice? Or will that just pause everything making it inefficient for multithreading at all and basically turn it into a timer), and what is the proper way to make the thread post the 'responseFromServer' to the RichTextBox1 in a safe way?

I can't get it to post at all because I know there's some invoke trick I can't figure out so I don't cross the threads like in ghost busters, and also if multiple threads are trying to post to it at once I'm going to need a protected way to do this.