I'm trying to learn about investing in the stock market. I want to get people's opinion on a few things

I have always wanted to invest in the stock market but never really got around to it... late happened. I didn't really know where to start or even where to start learning. I could have taken a class at school but that was different from my major nut I found a way to learn now. I wanted to get people's take on what they thought about margins and short selling