This is actually a cable modem with a local configuration page. This means that it can be configured through the browser. The problem is that since it's a cable modem, all ports are opened since it does not have a firewall to block the ports. However, go to Start > Run > type cmd and the following command: ipconfig|findstr "Gateway". Note down the IP from the only displayed gateway and paste it into a browser tab. A log-in prompt should appear where you need to enter admin/admin as a username or a password. If it's not working, consult the manual of the router. The port forwarding section should be located under Network > Port Forwarding. Add the ports, then specify the IP of your computer and they should be opened.
Note: This section might be missing because it's a cable modem and not a router.