Do you know the wireless settings of the router ?
If not then you will first need to know the wireless settings of the router.
For this you will need to connect the computer to the router with the Ethernet cable.
After that open the router set up and check the wireless settings.
Click here for step by step solution on how to check the wireless settings and how to connect to the wireless network

You need to access the ip address of the router create a wireless account. Contact your ISP for assistance in accessing the IP address of the router.

To connect to your wireless router, it needs the router’s wireless settings configured and also needs the wireless cards in all the laptops and or computers to be configured with the router’s wireless settings. Then the laptops and desktop computers can communicate with your wireless router.

To set-up and secure the wireless router from unauthorized access, follow these steps: -
1. Connect the wireless router to your computer with a LAN cable.
2. Start your browser and enter the router's configuration URL IP address.
3. Enter the router setup, login and password
4. Change the admin password
5. Go to the wireless settings and change the default SSID and turn off SSID broadcast.
6. Setup encryption key the strongest is WPA2 (if not then WPA).
7. For further security measures - turn on MAC address filtering and enter the MAC address of the wireless cards on the computer/s you want to connect to this wireless router.
8. Record the settings you have made and keep it in a safe place and Save the settings.
9. Configure the wireless cards on the computer/s with the SSID and encryption settings of the router.
10. Remove the LAN cable between the router and the computer then the computers should be able to connect to the router wirelessly.

To access the Internet you need to connect the DSL or cable modem to the WAN (Internet) port on the wireless router.