This is hilarious. The famous 5-minute install. I got as far as step 2 before you stumpped me:
Open up wp-config-sample.php with a text editor like WordPad or similar and fill in your database connection details
I think I have Apache, PHP and MySQL installed (no telling if they're configured properly).
As for setting the database connection details, I have no idea. I'm new to the Mac (although I doubt I would have understood this on PC either) so go easy on me.