It's very simple actually. Just copy the following code and paste it where you want the link to be.
Code
<a href="javascript://" onclick="window.open('http://Site_address/mchat','mchat','scrollbars=1,top=30,left=100,resizable=1,width=300,height=300');return false;"><b>Tag Board</b></a>
Now Replace "Site_Address" with your site address. You can Change the Width and Height to your liking.
