How to Add Your Own Music to Sims 3

Choose the songs you'd like to put in your game. Make sure they're all MP3 files and are 320kbit/s or smaller.

Copy the songs. Select the songs, right-click on them, and click Copy. Alternatively, hit Ctrl+C on Windows, or ⌘ Cmd+C on a Mac. You'll want to copy the songs, not move them - otherwise the music won't also be in the folders they were in previously.

Find your Custom Music folder. Access Documents, open the Electronic Arts folder, then open the folder titled The Sims 3 and find the folder labeled Custom Music.

Move all of the MP3 files to your Custom Music folder. Open the Custom Music folder, right-click inside the folder, and click Paste. Alternatively, hit Ctrl+V on Windows or ⌘ Cmd+V on Mac to add the files. There will already be files in your Custom Music folder, even if you didn't add anything previously. You can delete any files you don't want.

Start your game and play the Custom Music station. Have a Sim turn the radio on and choose "Custom Music" as the station. You should hear the music you added to your game.