The new message notification sound in WeChat can only use the system’s own sound, and users cannot add it themselves. The specific steps are as follows:

1. Open WeChat and click Settings.

2. There is "New Message Reminder" in the settings list, click on it.

3. Click on the new message prompt sound as shown in the picture;

4. There are many system music in the new message prompt sound list. Click to listen to it, and finally decide on the music to set. Check the box next and click "Save".

5. When the music you set is displayed behind the new message prompt, it means the replacement is successful.

6. If you need to turn off the sound, click directly on the sound position as shown in the picture. It will be displayed in gray, which means turning off the sound.