The "Wait 20" equals 1 second.
There are only 2 variables used that can be named to whatever you want. One is used for keeping track of seconds and the other keeps track of minutes. The wait will continually increase the "Variable Day/Night Seconds" by 1 until it hits 60, then it will increase the "Variable Day/Night Minutes" by 1 and reset the seconds so it can start the process over. When "Variable Day/Night Minutes" reaches 14 which is approximately 14 minutes, it resets the minutes so everything can start over and it would then be morning.
A picture is displayed for dawn, day, dusk, and night as the "Change Screen Color Tone" is used to dim the screen out or brighten it so it appears that the sun is rising and falling towards night time.
You will need to set a "Condition Switch" to turn this common event on, so just stick it at the beginning of your game or whenever you would like to turn it on/off to control whether the cycle of the sun plays a factor.
You need pictures to display. I will add in free ones below.
To change the times at which the 4 times of day appear, just edit the Conditional Branch Variable of the Minute (Of dawn, day, dusk and night) and change it to whatever you wish.