Open Opera, select the menu button then click Settings
Click Browser and then click on "Change Proxy Settings" under Network.
Now select "LAN Settings"
Set your settings to match the image below, our HTTP proxies can be found here
Click OK and then OK again - now browse to any website, it will prompt to enter your TorGuard Proxy username and password - if your not sure of those, they can be managed here
Browse to TorGuard Whats My IP and confirm your IP has now changed.