The way to include a notes section in your play is to write your notes in the Coaching Points section.
Adding Coaching Points in the Draw Tab
In the Draw tab, at the very bottom of the page underneath the Play Editor window, you will see a small black arrow. Click and hold your mouse on the arrow, and then drag your mouse upwards to reveal the Coaching Points section. This is where you will want to type your notes for the play that don't belong in the Frame Descriptions.
By default, your Coaching Points table will contain two columns, one for Pos and one for Description, and several rows. By right-clicking anywhere in the Coaching Points window, you can access more options, such as adding rows or columns, or deleting existing rows or columns.
Printing Coaching Points
When you go to print your play, click the Playbook Settings icon in the Preview tab. At the top of the menu, find the option for Print Settings and change it to Coaching Points.
This will include the Coaching Points section at the bottom of your page with the notes that you typed in. Change the Frames per Row and Rows per Page as you normally would to customize how the frames will look.