Adding Notes to a Job, Client or Location is quite quickly and easily navigated in the App.

In the App, go to Jobs > tap on the relevant Job which relates to all or either of those options (Job, Location or Client) > tap on the relevant section you would like the Note added. 

In the Notes, tap on the + symbol in the bottom right to add a new Note.

Alternatively, if you are in the Edit screen for a Job, there is a section where you can add a note which will be saved when you save the Job..

For Contacts alternative:

Go to CRM > select the Contact > tap the three dots in the top right > select New Note.

Or tap on the Notes symbol > tap on the + symbol in the bottom right.

For Locations alternative:

Go to CRM > select the Contact > select Locations > select the specific Location > Notes > select Add Note.