Login to your MySQL database via phpMyAdmin . Select your database. Choose the SQL tab. Enter the code lines into the text box and press Go. You will be provided with the results of the command on this screen.
Login to your MySQL database via MySQL Query Browser . Double click on your database on the right hand side to select it. Create a new "script" tab and enter the code lines into the text box provided and press "Execute".
MySQL by default ships with a command line client  that enables access to MySQL databases.
mysql --user=name joomla_database_name < diff_rc3_to_rc4.sql