I am new to crypto and I want to learn how to trade but I do not know where to start. Please give me some advice on what are the best exchanges where I could learn how to trade. Your advices will be highly appreciated. 
I respect with your desire to trade, if you choose the exchanger I suggest to adjust to your desires for example look more simple, if you want to find an exchanger that has a demo then I do not know, but I suggest exchange binance and bittrex because of the look that I think is simple.You are a beginner before trading you should understand the risks of trading and have people who can teach you because you need more experienced people to help you.