You don't need to add anything to her laptop for it to be able to connect to your router instead of hers. A router isn't installed in a PC, either as hardware or as software, it is a network device to which a computer connects.
To connect by ethernet cable, she would simply plug a cable between her laptop's RJ45 port and one of your router's LAN ports.
To connect "wirelessly", she would run the wireless adapter's software, scan for "Available Wireless Networks", find and highlight the one that matches your router's SSID (network name) and select the option to "Connect" to it. She should be prompted to enter any WEP or WPA encryption key and, once "Connected", the wireless adapter should get its IP address by DHCP from the router and should have internet access.