You cannot upload FileMaker files to this forum directly. As listed below Post A Answer only image files of specific file types may be uploaded. But you can upload the file to a file sharing site such as Drop Box and then post the download link to the file here.
I haven't checked the exact method used in that starter solution, but it sounds like you need to add a related notes table so you can then place a portal to Notes on your layout. This can be done without needing any script or Add note button or a script such as that discussed in this thread: Adding a new record to a related table in a script can be used to set up such a button.