Job notes are handy for saving gate codes, customer requests, job site photos, or anything else related to a job that you want to keep track of.
Start by going to the Jobs page and finding the job you want to add a note to. Once you're on the detail page for the job, click the blue popover menu button on the upper right of the page, next to the customer's name, and select Add a Note. This will take you to the new note screen where you can add the note's text as well as any photos. After finishing the note, press Add this Note to create the new note.