As the first step, you must add the new Slingbox to your Sling Account. Once you have added the new Slingbox, you need to launch the application on your iPhone and log in to your Sling Account. You will be able to get the two units listed.
The following link will allow you to know how to add a Slingbox to your Sling Account:
Make sure to follow these steps and let us know how it works for you.
Thanks for the response. I'll be sure to post the results when I get the second Singbox set up.
Sure happy with the first one I have set up here. Really easy to set up and get running. Even for this non-techy.