To insert a note on a device, go to
Ribbon: DM Electrical->Devices-> 
Insert Note
Pulldown Menu: DM Electrical->Modify Devices->Insert Note
You will be prompted to specify the device to which the note will be added.
Select device to add note to:
Insert Device Note Dialog Box
Enter the note into the Note field and press the OK button.
If the note is longer than one line, press the Edit button and enter in the entire note.
See the Inserting Notes and Leaders on the Drawing section for more information about inserting the note.