How do you put music onto an mp4 or where can i find instructions?

To add music to an MP4 file, you can use video editing software such as iMovie, Adobe Premiere Pro, or free options like Shotcut or OpenShot. Simply import your MP4 video, add the audio track, and export the final product. For detailed instructions, you can find tutorials on platforms like YouTube or check the official support pages of the software you're using.