Install WordPress local at Mac

Hi

I’m installing a WordPress2.3.3 en mi Mac.
I had an error message in install.php.
It says that it can´t conect to the database. (I´m running MySQL 5.0.51a)
The error is “Error establishing a database connection”.
I saw some posts with this problem but I couldn´t find how to solve it.
I suppose that wp-config.php is ok but is probably not.

What can I do to make the problem more specific?
Can anybody help me?

Thanks