Here is a tutorial to help you out if you are having trouble!
1. Create a new score
2. Write - "Year 9 Demo" for title and your name for composer.
3. Click in the first measure/bar and place a note in the first space.
4. Can you add these notes - change the note value near the top left.
Now that you can enter notes, collect a sheet from the front and see if you can input the notes into the correct positions.