I found out there is an easy way of doing that. You can follow this blog post which is providing a step by step guide to do it : Install Apache Tomcat on Ubuntu
Step 1:
Open the Eclipse.
Step 2:
Goto Windows → Preferences in the menu bar and select the Runtime Environments under the Server.
Step 3:
Click on the 'Add' button.
Step 4:
Select your Apache Tomcat version under the 'Apache' root and click 'Next'.
Step 5:
Browse and select the Tomcat installation directory.
Step 6:
Click on the 'Finish' button
Step 7:
Click on the 'OK' button to close the Preferences dialog.