I'm not familiar with either the 2Wire 2701HG-B or the ZyXEL, but this is generally how it goes:
Plug the 2Wire into your ZyXEL with the ethernet cable
(temporarily) plug your PC into 2Wire with an ethernet cable
Follow the instructions that came with the 2Wire to connect into the configuration page with your web-browser, and configure it..
Disconnect the ethernet cable
Make sure the wireless adapter in your PC is active.. Open your wireless adapter software and you should see the network name that you setup on the 2Wire when you configured it listed as an available network- connect to it, enter the password you put in while configuring your 2Wire, and enjoy the wireless connectivity!
... obviously this is short on details - do you have/have you read the documentation that came with your 2Wire router?
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