We give read / write permissions by issuing a command: We give read / write permissions by issuing a command. This incident will be reported

After Installing Debian. After typing sudo, the terminal displayed such an error:
debianpolska does not appear in the sudoers. This incident will be reported.
How to add a user to the sudoers?

First, we log in to the root account via the command:

su

we give our password.

We give read / write permissions by issuing a command:

chmod 644 /etc/sudoers

We give read / write permissions by issuing a command:

nano /etc/sudoers

We give read / write permissions by issuing a command:

User privilege specification

We give read / write permissions by issuing a command:

root ALL=(ALL:ALL) ALL

We give read / write permissions by issuing a command:

debianpolska ALL=(ALL:ALL) ALL

We give read / write permissions by issuing a command.

We give read / write permissions by issuing a command: