Normally, a system is just set up for private networks. It does have public Network settings, but they could be different from your private settings. There may be some setting there that would help.
Also, on the networks, it would need to be a public network listed in the Network and Sharing center. If you left click the wireless icon, is the network you are trying to access listed? Does it have any symbols next to it like a lock? Have you tried selecting "Connect"?