new (and exciting) territory

I've seen some posts regarding what servlets should and should not do. I'm starting to design a web app using servlets that prompts for data, stores that data in a table, and retrieves the data. Simple. I can right a bunch of servlets to do all this, but I want to do this the right way.
Servlets, databases, and web apps in general are all fairly new to me, so whats the right way to design servlets? What functionality should they handle and should they pass off to other classes?

I have a ton of other specific questions, mainly regarding the GUI, but we'll start here first.

FYI, I'm using OC4J and JDeveloper and can only use servetls, no JSF (no I have no other options).

Thanks