Noob - GWT And Libgdx

Well guys. Im starting to understand how to run my project in this gwt stuff…

I have 2 questions, please help me.

a) Each module/package of my code must have a gwt.xml ?

b) Do i need to insert :

<module>
<source path=""/> 
</module>

for each package-code?

What about packages inside packages?

-Please help