Hello,
I followed the following tutorial:lamp and when I have to connect to phpmyadmin, I don’t know what to enter in user and password.
When installing mysqld and creating the database, I did not add any password (since it is only for internal use).
So, for phpmyadmin, what should I indicate?
Thank you.
Without a password, it will not work. 
You should run the script provided to setup initial security