If you need to leave any communication regarding the job for other coworkers to read (or even just a reminder note for yourself), this can be done using the Notes section.
This can be accessed by clicking the Notes tab above the map on the right-hand side of the Job Summary screen:
Click the Add Note button at the bottom right to create a new note. The Add Note pop-up will appear as below. Enter the note details into the field provided. You may also add documents as attachments if you wish. Click Save Note when complete:
Saved notes will appear on the main Notes section as below. It lists the text of the note, when and who it was written by, and shows any attached documents:
To delete notes when they are no longer needed, check the box at the top right corner of the note, then click Delete Notes.