You can add a note either using the Web Portal or the App.
On the Web Portal you can add them via the Contact sliding modal if you don't wish to leave the contacts list, go to CRM > All Contacts > click on the edit pencil for the contact you wish to add a note to. An information panel will then open on the right side of your screen. Scroll to the bottom and there is a section for notes. Add the note and save.
You can then access the note when you go to the full Contact page.
You can add the note by going to the contact page via CRM > All Contacts > Select Contact ID or Arrow > Select Notes tab > select New Note.
(Please Note: You can also view all past notes by selecting the Notes icon. All notes added in the communication section in the contact card cannot be deleted.)
You do not need to select Notes in order to add a new note either, with the CRM Contacts Management Portal update, you can simply select the down arrow in the New option in the top right, and a dropdown will show you a list of all the New items you can create from the Contact Portal.
The Web Portal also has the quick creation options, in the portal bar at the top of the page, you can select the + symbol, and then select + Note. You will then get a popup, where you can select the Contact you want to add the note to, and the note information before saving it.
In the App, CRM > Search for and Select the contact > Select the menu button in the top right hand corner > New Note.
Alternatively, you can click on the Notes symbol, and select the + button at the bottom right corner.