I guess the admin/points section has all the needed information. Just take the number you've set for each category, multiply it by the multiplier at the bottom, add the initial points and the bonus per user (those are set while editing the user profile). That should be it.
The values for each user are stored in the ^userpoints table. Note the points column is used to hold the resulting value of applying the calculation.
The multiplier and initial points can be fetched from the ^options table. Check the options points_multiple and points_base.