I'll try and give you the general idea in a few steps, it is a bit daunting at first
1) Ignore all the numbers and columns except
the blue 'back' column. This column is just like the odds at a bookmaker except in the decimal format. To get from the fractional odds you typically see at a bookmaker to these decimal odds, turn the fraction into a number and add 1. So if you see 3/1 at a bookmaker that is the same as 4 on Betfair (in the decimal format)
2) So this column can be used like a bookmaker, if you click on one of these back numbers a betslip comes up to the right and you can bet on that driver to win the championship. The amount of money available to bet on that driver is the quantity located in the box and is the money of another pundit like you who is betting on that driver NOT to win the championship.
3) When you have an account you can easily experiment by keying in a bet because Betfair will overlay your exact position onto the market so you can see exactly what you stand to win/lose depending on the result
That should be a good start, I am quite experienced with this so if you are still interested/have further questions, I'm happy to help