MM.MySQL

I hope someone can help
I initialised my mac to make sure mySQL will work. However after istalling mySQL I try creating a database and I get the following error:
Welcome to Darwin!
[nikos-karaoulaniss-Computer:~] nikos% /usr/local/mysql/bin/mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 7 to server version: 4.0.16-standard

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> create database sampldb;
ERROR 1044: Access denied for user: '@localhost' to database 'sampldb'
mysql>


Any ideas?

many thanks