If you've already been connecting "wirelessly" to the router with your computer, it shouldn't be necessary to go into the configuration pages for your son's new Laptop to connect to it as well.
Assuming he's using Windows 7, it should only be necessary to click the Network icon on the Taskbar to see the available wireless networks and then select the option to connect to your network.
If you are trying to access the router's configuration pages, are you doing it from *your* computer, which will already have an IP address allocated by the router? Typing in 192.168.1.1 from your son's Laptop, if it hasn't already connected to the router to get its IP address, isn't going to work.
How to watch Wimbledon 2015 live online: follow the tennis from your laptop or PC