Ashish, you did not provide information which language/technology you use. If Java, then read doc about working with databases. You should have driver for MySQL, JDBC for example:
Connection string can look: con = DriverManager.getConnection("jdbc:mysql:///test", "root", "secret");
If PHP, than should works with mysql_connect function. Check manual for PHP. However Tomcat as web server for eZ publish is not supported.
And, your question is not related to eZ publish, and supported by eZp technology.
