There are many tutorials and videos available on youtube for beginners which will teach you the basics of bitcoin trading and after watching multiple videos it will surely add value to your knowledge related to trading and you can start with a small amount and start gaining a practical experience.
In fact, bitcointalk.org I think is enough for you to know everything about in bitcoin, trading, and others because it is very informative. And youtube is also helpful as stated above mentioned.
In youtube we can understand step-by-step review and trade bittrex poloniex, and through bitcointalk we can follow the progress development in altcoin announcement. Bitcoin trade isn't complicated, just buy and sell price fluctuations. What is interesting is trading in altcoin because its more challenging. At first I was immediately plunged into poloniex and yobit to see patterns in advance, its not difficult to study directly, but must be at least a deposit in advance.
"learning by doing not need a lot of theories"
The most important references is to see available supply of coins that we want to buy, we clearly can read the complete information about this in coinmarketcap. Volume of transactions also greatly affects the coin stability.
For learning trading through youtube isn't enough in my opinion since it's difficult to choose which basis we shoudld follow in youtube, hence we can't easily get all information we would need. However, if thou must study it through an article or forum, you don't just learn how to trade but also you'll be updated what is the best coin to trade in a certain time.