Aplication on default site

[teilor111]

I have aplication on server Tomcat (in debian) and when it is in
/var/lib/tomcat7/webapps/Aplication/WEB-INF >> web.xml and in folder classes I have Aplication.class . Now when open browser and type: IP:8080/Aplication/Aplication - my aplication is OK, its work, but... I want to make it, that after type simple: IP:8080/
I want see my Aplication. I change ROOT folder to other name and my folder Aplication rename to ROOT, and I cant see my Aplication, why? I cant run it with .classes and .java files, i need .jsp o what? How i must set it?

(IP:8080 want show index.html or php but i want aplication .java or compiled: class)

Thanks for any help