Aerodynamic resistance is somewhat more complicated. The most significant aspect is that it depends on the square of your air speed - the sum of travel speed and headwind. You multiply this value by a coefficient that depends on an aerodynamic shape factor, area and air density.
Power is the product of force times velocity.
So, you add the three forces above, and multiply by speed. If you convert everything properly to metric units, you get watts. I wanted to predict speed from power, however. The power calculation is a cubic expression, meaning it is not easily re-arranged to calculate velocity directly from power. One of the spreadsheet programs can represent a course with multiple legs.