First, open the location of the wallpaper by opening wallpaper engine and right-clicking the wallpaper you have downloaded. Click 'Open in Explorer' from the options that show up.



Depending on what you see, you'll have to take a few different steps:

If you see a file titled "scene.pkg" anywhere in there: then you will have to unpack the wallpaper files. First, copy the files titled "preview" and "project" and paste them into a new folder on your desktop, named like the wallpaper. Then you will upload the "scene.pkg" file to this website (link)[wetranslate.thiscould.work] which will return a zip file of the wallpaper components. Then you can open the .zip and copy all of the files from inside of it, and paste those files into the folder you made on your desktop earlier. Drag this folder into the wallpaper engine projects folder (located at "Steam\steamapps\common\wallpaper_engine\projects\myprojects"). Then this unpacked copy of the wallpaper will appear in your installed wallpapers when you open wallpaper engine (close and reopen wallpaper engine if it's not showing), and from there you can open it in the editor and change whatever you like - including just clicking "Add Asset" and selecting "Sound" to use the music downloaded for it, the music has to be in MP3 so if your music is not in MP3 use an online converter to MP3.





If the wallpaper already has a sound you can change the sound by clicking in it and loading a new sound, removing the other sound and changing the name of the asset. Or you can just remove it and do the "Add Asset" process.



If opening the wallpaper in explorer shows a type of video file: then you'll have to add the music to the video using a video editor like Lightworks or Adobe Premier Pro but i think that windows has a video editor tool so you can use it. With this way, after using 'open in explorer' you'll copy all of the files inside of there and paste them to a new folder on your desktop named after the wallpaper. Then you can open the video file in this folder and edit it using any software for video editing, just having to add music to fit the video length. After exporting the video from the editor, you will place this final video into the folder you made earlier and then delete the old video that was already in there. Drag this whole folder into your wallpaper engine projects folder (located at "Steam\steamapps\common\wallpaper_engine\projects\myprojects"), and you'll see it show up as a wallpaper you can use (close and reopen wallpaper engine if it's not showing). If you want, you can even open the wallpaper in the editor and publish it to the Steam Workshop for others to use.

If you want to start the song instantly when you open windows go to settings, general and choose the high priority option.

I hope this isn't too confusing, let me know if there's anything I can explain or guide further.
Share this guide if you find it useful, an upvote and a reward is always apreciated.
Enjoy your wallpapers :D