Help getting eathernet to my pc upstairs

[CauselessMango]

So recently I have tryed to setup ethernet to my pc upstairs yet it seems that there is no internet coming through the port. Nut I have no idea where this cable comes from. Also would I need a modem/router if I wanted internet up through it?
http://imgur.com/LVt30EG
http://imgur.com/kCqn09J
Here is a picture ot the box outside that It appears the cable may come from. (router is downstairs)
http://imgur.com/b0ddp9j
http://imgur.com/csD9w0o
Here is my router/modem. (downstairs)
http://imgur.com/csD9w0o
http://imgur.com/mjnHt86
Any help is appreciated. Thank you.
Any help is appreciated. Thank you.

 

[jsmithepa]

http://imgur.com/mjnHt86

Remove this plate and show us the cable(s) behind.