Apache Tomcat - Permission Problems

I downloaded apache-tomcat-6.0.24 and i extracted the contents
of the zip file.

Then I typed the following comamnds

cd apache-tomcat-6.0.24
cd bin
sh startup.sh

When i executed this step, I got the following Error.

Cannot find ./catalina.sh
This file is needed to run this program

I searched the forums and found the following solution.
Reference:
http://codingexplorer.wordpress.com/2009/01/12/the-basedir-environment-variable-is-not-defined-correctly-this-environment-variable-is-needed-to-run-this-program/

Just type the following command.

Note: 
You need to be in the bin directory.
(i.e) Your Path should be

cd /opt/apache-tomcat-6.0.24/bin

chmod 777 *.sh

After this, when i executed the startup.sh script,
My tomcat server was starting.