Supply and demand move stocks. If there is more demand for a stock than the supply then the stock goes up. So how can you tell if there is more demand vs. supply. If the security/commodity that you are trading trades above the opening range and holds for half the time that you define as the opening range then there is more demand than supply.
Have a look at an example, MolyCorp.
First thing you have to pay attention to is the opening range, this concept/indicator takes major precedence over the support or resistance determined by the prior day (blue lines) always.
So what happened today? Market defined an opening range, broke below the range (down day). Now, it can be dangerous to bet against the blue lines (support) BUT, if it goes through the blue lines then that is extremely bearish.
Summary: Not only are the green lines denoting a bearish outlook for the day (more supply) but the fact that the market sliced so quickly through resistance shows extremely heavy supply.