You should take a look at this guide. and this
I think you've installed jre, jdk and downloaded tomcat.
Then extract, and move tomcat folder to a permanent location as u like : for example ,
sudo mv apache-tomcat-6.0.14 /usr/local/tomcat
okay, Tomcat requires setting the JAVA_HOME variable. The best way to do this is to set it in your .bashrc file. You could also edit your startup.sh file if you so chose.
The better method is editing your .bashrc file and adding the bolded line there. You’ll have to logout of the shell for the change to take effect.
Add the following line:
At this point you can start tomcat by just executing the startup.sh script in the tomcat/bin folder.