Maybe things are easier in the US, butr I'm so afraid of oversimplifying navigation, especially at night.
Have a look at this map.
I have put in the letters A
to mark two different white sectors.
Note that when you are sailing
-towards the light in sector A
you have red on starboard and green on port side.
-towards the light in sector B
you have green on your starboard side and red on port side.
In general the white mark the primary go zones and both green and red mark bordering zones.
This does not imply the the red or green zones is in navigable but you must look at the map to determine when the colored zones are navigable. At night you should use other light sectors or lights to find out when you are in "free" water.
It would be highly irresponsible to sail in waters like this day and night without some basic navigation skills.