Let's get started!
Disclaimer:
Due to the wide variety of devices available and potential variations in their firmware, the information presented below may or may not be accurate. For this same reason, OpenDNS support will generally not be able to provide device-specific assistance beyond what is provided below. If you need further assistance specific to your device, please contact either the manufacturer's support team, or your ISP if you are using leased equipment.

THE MANUAL:
This document is based on the Belkin AC750 DB document with firmware version: F9K1116V1. (click here to download PDF)
- Log into your Belkin router by typing the IP address in your browser's address bar: http://192.168.2.1 (page 4 in manual)
- Locate the WAN Settings menu tab and choose ISP Connection Type (page 15)
- On the page where you can select your connection type, click the tab DNS
NOTE:
If you need to choose the connection type to proceed to the DNS tab, select the appropriate connection and click next to proceed to the next page.
- You should see a fields to enter two DNS server IP addresses. Set the first to 208.67.222.222 and the secondary to 208.67.220.220
- Save your settings and the router will reboot.
- To test your settings
Okay, now what?
To ensure that OpenDNS is working properly for you, please flush your browser and DNS cache by using the steps below:
http://www.opendns.com/support/article/67
http://www.opendns.com/support/article/68
Next, let's test your settings by visiting http://welcome.opendns.com, you should be greeted with a Welcome message.

ISSUES?
If you run into any problems, please feel free to contact OpenDNS support at http://support.opendns.com. To help us look into your issue quicker, please run the diagnostic tool using the URL's below. When the tool completes, copy the results URL from the tool and paste it into your message.
Mac: http://www.opendns.com/download/mac/diagnostic
Windows: http://www.opendns.com/download/windows/diagnostic
Welcome aboard!
Your network is now safer, faster and smarter. Use the OpenDNS Dashboard at https://dashboard.opendns.com/settings to help you customize your settings.