Howdy and welcome aboard.
I would really suggest that you hop over to the modding section and then read some of the threads that show a flashlight build from top to bottom. This way you can see some examples of how it’s done. Here is a link to literally hundreds of builds that people have done and all in one thread to, so it’s easy to look around.
After you get all the basic ideas down, then you should just go ahead and pick a project for yourself. Then ask away and you will find tons of people here who are willing to help talk you through it. It’s pretty hard to help you right now though. You need to get at the basics first. There is no way to simply learn everything right away, it’s too big of a topic and to be honest none of us know Everything. All of of us have a piece of it and pool that knowledge to help out.