posts and archives

Hi,
I’d like to create a Newsletter page for my site. The page would contain the whole of the current Newsletter (it’s quite long) and in the right sidebar I’d like to have a list of all the previous Newsletters that can be viewed.
I’m supposing the page needs to be a post. But how do I configure it so that there’s only ever the current Newlstter on the page and all the older ones in the sidebar?
Thanks!