Since Microsoft shut down its game server service for CFS3 the only option for online players is IP-to-IP games (Join Private Game on CFS3's Multiplayer menu). Vista and Windows 7 will not allow a program called CFS3.exe to connect online, so follow the instructions in this thread to get online.

If you prefer video guides, Tailwind's excellent videos are linked velow.

This thread combines information from previous sticky threads by Deadmeat1971, Blacksheep-ghost03, Tailwind, Grizzly50 and others.