You will need to have a computer running, to be able to stream content over Internet. The PC must be running MC, and it have to have the Media Network features turned on. You find this nder Options. At the same time you need to enable some port forwarding on your router, to be able to contact the PC on your internal network. You see the Port used under Media Network options, and you can google how to enable port forwarding for this exact port on your router.
First you need to ensure that you can stream content from your PC on the internal network. You can ask here if you can't get it to work. But it should not be difficult. Activate Media Network, write down the access key, select Authentication and give a username and password. Then you try to connect with another machine, or an android phone or tab with Gizmo. Choose to connect to another library and enter the access key and the username/password. When that works, you'll need to do that port forwarding on the router. There's to many models and ways to do this, so you'll have to google it for your router, or to ask on the producers forums or something.
Good luck.
