http://www.hydroponics.net/learn/co2_calculator.asp

You can figure it out there.

Oldsanclem is correct. You are looking to ad about 1500 ppm and there is about 300 ppm in the ambient air so that will give you a total of 1800 ppm.

The idea is to raise the level and hold it at that level for many hours so the plant has time to absorbe the extra amount. You will need to rase the temperature to above 85f but not above 95f for the plant to absorbe it easy and get the most out of your inventment.