My Ubuntu 12.04 installation has an input problem resulting preventing me from clicking near the top of the screen. That is, there is an unclickable area, circa 60 pixels high and stretching all the way across the screen. I will ask about this in a later question.

For now, I would just like to be able to connect to the internet, given this limitation. I am able to access the network connections application by hitting the super key and typing "network connections". There is a LAN and a wireless network available.

The network icon in the bar at the top of the screen shows an empty wedge, which I suppose means that wireless is off. I've attached the cable for the Ethernet connection, but it does not seem to have connected automatically. How can I figure out what's going on?

(I'll happily edit in the output of any relevant terminal commands.)

Thank you.