I'm assuming that you installed the driver, not just copied it? If you download the driver to your flash drive and copy it over to your other PC, you still have to open it up and run it to install it or it won't work. For windows 7, Click Start > type "Network and Sharing Center" and press enter > Click the "Connect or disconnect" button and a window will pop up on the right hand side > Double click on the network you want to connect to and you're done.
If it's password protected, enter the password. If you entered the wrong password (double check that you spelled it right) go back to the step where you double click the network and instead right click the network and click properties. On the "Security" tab there will be a box...