How do you create a new topic in jforum?
ON the home page (possibly
http://localhost:8080/jforum2/, which redirects to
http://localhost:8080/jforum2/forums/list.page) should be a link to one forum called "Test Forum". If you click on that, it'll take you to a list of all topics in that forum, and
you should see a button labelled "new topic", both at the top and at the bottom - clicking that will let you create a new topic.
And how to change the page design, i mean in which file are they in?
In the exploded war file, there's a top-level directory called "templates", in which you'll find a subdirectory called "default" which contains all the page templates in
FreeMarker syntax. The CSS files are in a subdirectory called "styles".
How to connect it to Oracle?
It's a bit tricky to change this after JForum has been installed. The easiest would be to reinstall it from scratch, and use the JForum installer to configure the DB.