It seems that you are having some issues in order to set up your Slingbox SOLO for Internet Viewing.
First, you will install the Slingbox on your own home network. Then, you will reset the Slingbox in order to clear out any old setting. Once you reset it, you will run the Setup Assistant for Internet Viewing.
You do not need to worry about your friend's network. Once you reset the Slingbox, you will set it up on your network. The following links will provide you with all the information you must know about how to set up your Slingbox for Internet Viewing.
How to reset your Slingbox to factory settings