To secure your wireless network, you’ll need to change the user name and password on your router, and make sure that everyone uses user names and strong passwords on their computers. They should always use a user account, instead of an administrator account, and the guest account should be completely disabled. Also make sure that all of the computers have software firewalls on and running. Now on your wireless router, you want at least WEP encryption going at the very minimum. Here is a weblink that explains how to do this better than I can.