Every beginner’s focus should be on obtaining knowledge from wherever he can. Remember, learning is never enough. The more you learn, the better you get at making decisions.
Not only for the beginer, but every trader, the best way to be good at trading is to practice is on the Demo account. As you mentioned, you forget once you read, so you should do it on your demo account so that it is for a longer time. Also, there is no risk involved, so it is always better. All the Best!