The bounce happens because of the dead spot in the pedal stroke at the bottom dead center. The idea is to try to get the pedal past that spot as smoothly as possible. One trick is to try to pedal in circles instead of squares, to do this some people suggest using a "Wipe your foot" motion at the bottom.
You just started biking and fixing the bounce doesn't happen overnight. You just have to keep working at it, keep pedaling at higher cadences and eventually it will smooth itself out.