phpMyAdmin is a tool written in PHP intended to handle the administration of MySQL over the WWW. Currently it can create and drop databases, create/drop/alter tables, delete/edit/add fields, execute any SQL statement, manage keys on fields, manage privileges,export data into various formats and is available in 46 languages.
Here's a beginner's guide to using phpmyadmin: http://www.siteground.com/tutorials/phpmyadmin/
Note that almost all web hosts already have phpmyadmin installed for your use. In CPanel it's frequently beneath the "MySQL" area. In the rare event that your host doesn't have it you may want to install it yourself.
The phpMyAdmin project