To create sheet music on GarageBand of Hot Cross Buns or other Soft Mozart music, create a new songwriting file (click on songwriting in GarageBand). From there, you can either play your piano keyboard and record what you play using MIDI (this is less time consuming if you are playing something with lots of notes) or you can input manually using your computer. Below, I am describing how to manually input the sheet music.
After creating a new songwriting file, click on the piano picture (so it records a piano track instead of drums, guitar, or voice) and click on the scissors icon at the bottom of the page. The scissors icon makes a piano roll appear on your monitor so as it records, you can click on the piano keys on the monitor for the music you want to record. To actually record, press the red record button and starting clicking on the piano keys on the monitor.
If your music is not perfect, it's not a problem. You can fix it later. Also, if you want to delete a drum track or any other music, click on drums and press delete.
To view the sheet music you have created so far, click on the word "score." (You may find it near the word Piano Roll and near the keyboard that you just played). If your music is not exactly as you want it, you can drag the notes to the proper place on the staff. You can also add more notes by highlighting one note and pasting it on the staff where you want. To paste a note, you need to make sure the red bar line is where you want the note to be.
To print your music, click on your sheet music staff to make sure the sheet music is highlighted. Go to File, Print, Preview. You can view it there and print. To save, go to File, Print, PDF, Save as PDF.