Why won't this cable work?

[wibtr]

I'm trying to plug a cable from my modem to my pc. I have 2 pcs. On one PC it works fine, i get online when i plug it. I switch the cable to the other pc and nothing happens. i dont get a connection. am i sticking it in the wrong hole? it was wireless before so i have never put a wired connection to it. here are the pics of the hole im trying to put it in. its the only one i see. Is that the right one? thanks.

 

[strategic]

Try a different cable or look to see what the network connection icon shows in the system tray. You're plugging into a RJ-45 jack, which is correct since the RJ-11 (phone line) is smaller and you won't get the plug to go in. I don't see any lights which normally appear next to the RJ-45 jack, that would have been another indication of connection.