Take all your audio files and make sure they are in GarageBand along with your singer's audio recording. For all of your audio files including multiple vocals, musical typing, iPad/iPhone instruments you must have a video of the person playing them in order to include in the song video compilation and for proof.
Organize your GarageBand layers in the following order and label them according to the names in quotations below:
Arrange your recorded music to line up with the original song. Apply at least one vocal effect to your singer's main vocal track like the screenshot below (vocal effects on the left, icon top left).
Take a screenshot of your GarageBand timeline like the one above when it is finished and upload to Schoology.
Then open each of the four videos of your musical typing and musician on the screen at one time using Quicktime and take one screenshot like the example below to upload to Schoology.