if you want to know about trade, then I will say that trade is simple buying with lower price and selling them at higher price. and for remaining details you can see the detailed tutorials available in various articles available on google.
What are you talking about? You are confusing OP, trading is very risking, and cause of that high risk its like gambling.
OP asked "why its risky?", simply cause its not easy to catch moments when its low and when its high. Its easy for us to talk about price going up or down, when you need to invest more then 1000 $ your hands are shaking in either way.
Don`t get into trading if you are not ready to risk on information`s that you found on internet or any other source. Cause that is what bitcoin trading is, you buy or sell in the moment when all your info make a feeling in you about changing of price, for that feeling you need to know the game.