I would highly recommend watching the video provided so you can see the fire of ring & get an idea of how fast you need to be, but with that said feel free to read the guide below as it's fairly simple ^.^
Firstly you want to load up the track "Braking Bad" level within the United States. Once you start the track, you want to reverse back until you bump into a button turning the ring of fire on, once pushed you need to race through the level as quickly as you can, as you will continue along the track you will eventually jump the train, driving up into a wrecked train. Once you come out of the train is the time where the ring of fire should pass by for your first chance at jumping through it. If you are too quick, & jump before it passes, continue to the next jump & try again as you have a second chance.
If you crash at all in the level or don't manage to jump through the ring of fire simply restart the level & try again, making sure to push the button each attempt.