What is an example of creating an admin panel?

Question

Java

Hello!
I'm learning Java EE.
I'm making Spring examples . Started learning Vaadin .
I want to make the admin panel simple.
Could you please tell me the tutorials, according to which you can create an admin panel, which involves working with the database, uploading files to the server, working with sessions.
Interested in the architecture of building this application.
THANK YOU!!!

Answer 1

well, how .. draw an oval, draw the rest of the owl!
one
two and google :)