Like Sal said.
There are (3) "divisions": A - B - C
You pick (2) drivers in Div. A
You pick (4) drivers in Div. B
You pick (2) drivers in Div. C
Of those you picked, you can actually only race 1/2 of them.... (1) A, (2) B, (1) C.
However, you do get 'some' points for the drivers that are not being "raced".
The points work like this:
Qualifying:
10 points for Pole
5 Points for Outside Pole
3 Points for Third Qualifying position
1 Point for Fourth Qualifying Position
Racing:
10 Points for Leading any lap (only get this (1) time per driver per race)
10 Points for leading Most Laps
90 Points for the Win
88 for Second
86 For third
2 point drop for every position, so 43rd place gets 6 points
You can race any driver upto 9 races, after that they will not score any racing points but can still get qualifying points... so you may not want to race Jr. or J Gordo the first 9 races as then they will be used up. But that's up to you.
The lockout date for selecting your roster is typically 2am Pacific Time on the night before qualifying. The lockout for choosing your "racing" drivers is 5 minutes prior to the posted race start time.
If you don't select a roster prior to the deadline, your drivers from the previous week will be used. If you don't change your racers, they will be used. If you don't check the boxes next to a driver, they will not race, therefore no points.
Yahoo has all the rules posted in the Fantasy Racing area. IF you have specific questions, please feel free to ask them here. Some of us have been doing the Yahoo Fantasy Racing for several years and pretty much know the quirks of the system.
So people (like me) do a metric $&it-ton of research on which drivers to pick each week. Other people just wing it and whoever they have a feeling for is who they select. There is no "right" answer to how you pick as the track records for this website is pretty broad... I don't know if anyone has repeated as league winner. I won one year, and have two 3rd place trophies.