As of the current build (February 5th, 2025) you can't "add" new music to ChillPulse, you have to replace the existing music with your custom music.

If you're downloading youtube videos, I recommend Stacher[stacher.io], as you can simply paste a youtube playlist, and it'll basically do the rest. (Check out the Stacher Section of this guide for more details. )

I also recommend making a new folder and putting all the music you've got in there for the next part

If you're using Stacher[stacher.io], make sure you've selected the outputted files to be "audio only", and select "vorbis" as the format.

It'll also probably ask you to install ffmpeg, in which case just click the button on stacher, and it'll take care of it.

You'll also want to go into settings (little gear icon in the top right), and then select "Metadata", then turn the setting "Add Metadata" on, it'll help you identify which songs you've replaced later on.

• Go to ChillPulse in your library, right click it, select Properties, and then hit "Browse Local Files".
  
  • This'll open a window of your file browser.
• Now, open up that folder with the music you want in ChillPulse.
  
• Copy the name of a music file in the ChillPulse folder, and use that to replace the name of one of the songs you want to put in ChillPulse.
  
• Now, copy the newly renamed file into the ChillPulse folder, it'll then ask you if you want to replace the file in ChillPulse, say yes
  
• Keep doing this until you have replaced all of the songs in the game you want with your own music.