No matter what is on the web and how much we will try to explain to you, unless you go and start cooking, and burn or undercook few things/dishes, few times or more, you are not going to understand what is going on. Sad, but true I know.
Here is your homework. Put a pot of water on the stove, bring to a boil then turn the heat down to lowest setting and cook it for 15-20 minutes, observe, take notes. Dump the water repeat the procedures this time turn the heat down to setting one above lowest. Repeat as many times as many settings you have on the stove. Record every time. I hope you have a digital camera. Save every file, store on your PC. Better yet create account on YouTube and upload there. Report back here when all the videos on the web. From there we will be able to help you more as far as simmering going. Otherwise it is empty talk, you still do not know what we are talking about and we cannot tell from here what the real simmering looks like.
P.S. Try the same with lead open and close.
You are what you eat.