Welcome to UF.
So you are typing
into one terminal and then, into another terminal
And at the point of being given a 'bound' IP address the Ubuntu Software Centre 'sees' the connection.
sudo dhclient easytether0
Let's verify that only Ubuntu Software Centre can 'see' this connection - I imagine you've opened a browser and gone for good old www.google.com from it, please say so and that it did not resolve.
Please post back results of following commands in terminal ('passive' commands, they ask for info, they don't set anything...)
Please copy and paste the results of the commands I have given you into your reply using this format: [code]<PASTED-CONTENT-HERE>[/code] to make it very easy to read and to distinguish between your text and 'system' text