Make sure to keep the same layer format from the GarageBand Arrangement directions.
After you have edited your final song, open Quicktime and create a screen recording while playing the entire song showing the Garageband layers (example video). If there are layers at the bottom that do not show, scroll down while the music is playing the screen is recording in order to show those layers at times during the video.
Then save and import the screen recording video into iMovie and match your mp3 final song to the screen recording and export the video file and upload it to Youtube and the link to Schoology. Then upload the mp3 song to your SoundCloud account, make the file downloadable, and post the link to Schoology. Insert the front cover of your CD as the cover art for your song on SoundCloud.