Firstly, you can’t really compare a RTS game like Warcraft with a shooter like Fortnite. That said, it is necessary to understand at least some basic concepts of the game in order to obtain wins.
(I wonder, if you would also complain about losses, if you would try to solely kill players in first-person-shooters with a knife all the time while they shoot you with fire arms!?)
Be it as it may, others already pointed out some places where you can learn more about the game.
Additionally, I would recommend you that you organize your hotkeys, since this upgrades your performance by a lot and makes the game-play much more fluent. E.g. I control the 12-field-command-window with 12 keys on my keyboard (QWER-ASDF-YXCV), which gives me much more freedom to concentrate on the game itself and the micro management of units