After the 2 first article dedicated to the global sense of trading: " is simple " and the choice of your first "strange partner" (the broker), we will speak about losing.
Indeed Trading is a matter of what you will lose. To stay in the game, you need to control this aspect. How much you will lose when you will lose because you will.
For that, you need to understand some basics figures and computations you will need to know to see where is your risk.
Indeed you will choose the amount of money you will play - the lot size - thanks to the risk level you will take.