If your player scores a touchdown, he'll bag your team 6 points.
For every 20 yards of passing your QB manages, he'll get 5 points. Each touchdown pass he throws earns you 3 points.
For every 10 yards of rushing your RBs manage, they'll bag 5 points too.
5 yards of receiving is worth 1 point to your WRs.
A field goal will earn your K 3 points, and an extra point will get him 1.
A take-away (interception or fumble recovery) will earn your DEF 5 points, and a quarterback sack is good for 3. Note that a take-away returned for a touchdown is good for 11 points (a sack which causes a fumble, which is then returned for a touchdown is worth a massive 14 points).
As an aside, in a complete reversal of last year, my team has been awful in week 1. I am relying on Joseph Addai having a monster game against Da Bears.