you need to substitute your MySQL username for username@'localhost'.
On my server, i use the 'root' user, with a password of '123'
so the SQL is:
GRANT SELECT ON dbname TO 'root'@'localhost' IDENTIFIED BY '123';
you also need to change dbname to the name of database to add the select privileges to. In my case the name of the database is 'ps3':
GRANT SELECT ON ps3 TO 'root'@'localhost' IDENTIFIED BY '123';