sorry, I'm at work so can't give very specific examples/advice, but I'll do my best to help anyway
You don't need to do anythign with your phone or on the device you want to use to connect WITH.
All settings need to be changed on the machine running the library server, and the router and firewall. If you don't have access, you're not going to be able to do this, sorry.
My router allows me to make changes by connecting from any machine on the network, so assuming you can also do this, you're still in business. I connect by typing 192.168.1.254 into the address bar of my browser. the IP address of your router is likely similar, but not the same.
Assuming you can gain access, this link does a better job of explaining how this works, and what changes you need to make.
http://wiki.jriver.com/index.php/Network_AccessRespond back with specific questions if you get stuck and someone will try to help.
Good luck, it's worth the effort!!