To add a Slingbox SOLO to your account, you would need to access a specific site. I have linked the setup page, as well as a video of the setup procedure below:
After you are on this page and logged into your account, you will be able to setup your Slingbox SOLO; please keep in mind that you will need to have both the Computer and the Slingbox connected to your router via Ethernet to complete the setup process.
I hope this helps!
Sling Media Technical Support