You want to pencil in the notes correct? If so try this.
1. Create an new empty Midi Software Instrument Track
2. Command Click in the Track Lane to reveal a Pencil tool
3. This will create a Region that you can drag out to any Bar length
4. With Region selected open the Midi Editor window and Command Click inside Grid to Reveal a Pencil tool
5. Now Pencil in the Notes, Drum Beats etc.