Dear Yaksh,
Check below replies for your questions:
So my first question is where is this webapp folder?
first you must use the tomcat installed inside the composer folder as it has some jars related to composer in its lib folder
also you must the the webapps folder it self, but when you deploy your application from the deploy button in the eclipse you will not find it the webapps folder, but you can check it from the tomcat admin UI
Second, how we can start bundled tomcat server?
you can start it from the bin folder under tomcat folder inside the composer folder installation path, use startup.sh or startup.bat, then check if tomcat started or not from your browser like "localhost:9090"
Third, do we need to add manager-gui role in configuration file tomcat-users.xml?
yes,
additional thing, you have to configure this tomcat in the preferences of eclipse under composer>tomcat and add there the requested info.
------------------------------
Omar Elhawary
------------------------------