You are going to need to provide more context. How are you trying to connect (browser, connector, standalone app)?
If you are trying to do connect directly in the browser like http://localhost:3306
, that will not work. You can directly use the database with phpMyAdmin from here http://localhost/phpmyadmin
assuming Apache and MySQL are both running. You can use the databases though the MySQL connectors/drivers in PHP or other programming languages directly using the relevant API. You could also use the MySQL console/GUI applications to work with the databases.