First things first you need to connect to mysql service:
mysql -u root -p
After that we can create an user:
CREATE USER 'username_here’@‘%’ IDENTIFIED BY ‘password_here’;
Then we have an user and now we can set all privileges to the user:
GRANT ALL PRIVILEGES ON*.* TO ‘username_here’@‘%’ WITH GRANT OPTION;
It's done! You have an user with all privileges set to the user.