Notepad pages are not encrypted, but if you use a secure login, then any information sent between you and FastMail.FM will be encrypted. Since only you have access to your FastMail.FM account, only you will be able to read the notepad pages.

To add Notepad pages, in the listbox on the left, double-click the < Create new > item at the top of the listbox. Alternatively, click on the < Create new > item and click 'Select' button at the bottom of the list. This will take you to a new screen with empty/default-valued items on the right hand side. Fill in the values, and then click 'Save' to create the new item. If you want to create another new item, click 'Save and create another...'.

This marks the note you are editing as a quicknote, which can be inserted into your mails through the Compose screen. This makes it easy to send people often-used information.