Yes, there is a relationship between weight and sail size. However, it is also affected by wind speed. (Stronger wind = smaller sail.) I made a spreadsheet that will calculate the correct sail size for your weight and the wind speed. Check it out:
It says that a beginner your weight should start out with a sail around 4.0 meters squared in winds less than 10 knots, or a smaller sail in winds greater than 10 knots.
It can also help you figure out what size board you need.