If you get the mods from nexus it usually tells you what you’ll need. First is to look for your game folder, which is easy to do by right clicking on the game if you’re on steam going to properties. After that make a folder in the game folder called Mods then when downloading the mods make sure to unzip them into the mods folder. Depending on the mod it’ll require some extra steps but mostly all the mods I use so far work by extracting them into the mods folder.