You can see your mods in game by left clicking on your selected sim - which will then showcase any mods and mod options you have in your game. You can disable this pop-up, but it might be useful when it comes to double checking that your mods work and will show up in the game.
There should be a pop-up when you load the game up, which will showcase all of the mods and custom content you currently have running on your game. Restart The Sims 4 - you will need to do this so that your new mods are launched along with the game. Drag all of your extracted files from this mod into your mod folder. Navigate to your documents folder in a new window, click on ‘Electronic Arts’, then ‘The Sims 4’, then ‘Mods’, which should showcase a folder with all of your mods in it. Open your Downloads folder and unzip your mod, by left-clicking it and selecting ‘Extract’. The Sims 4 folder automatically generates a new Mods folder after you. Make sure your mods are ones that people are using and talking about (like the ones we’ve suggested below), so you don’t download anything that might be harmful. The copied archives will then be shown in the mods folder where they can be. You can find mods from The Sims Resource and various smaller creator’s websites as well.
Download a mod of your choice into your Downloads folder.