You could have copied/pasted the error message onto here, we didn't need a screenshot ...
Still, your problem initially seems to lie with your database.
Mysql governs itself and which user can do what with a database called "mysql" where permissions are stored. You will have to either set up a user called 'nff' with the correct permissions, or, find out your default root password and locate where the database settings are stored in your application and alter the credentials from 'nff' to root or whoever you have granted access to all your tables to. That is the swift and dirty way to get permission to access and do things.
If you want to get to the bottom of this, and understand what causes this error message then this might help you too: Access denied for user and the permissions system