So, you'll need to find where you installed Monster Hunter World. If it's the default then you go to C:\Program Files\Steam\steamapps\common\Monster Hunter World\ Once you are in the Monster Hunter World folder, you will then create the nativePC folder. You drop all your mods in there and if the Mod Author did it correctly you should be able to extract the files that are in the nativePC folder and drop them in your Monster Hunter World nativePC folder. From there you should boot up your game and the mods will be there.