Java DB Netbeans Help

[vivek4020]

Hi I am just learning Java DB Database in NetBeans IDE 6.8

I am following this tutorial

http://netbeans.org/kb/docs/java/gui-db.html

The first problem is when creating the database and adding a table to it

I was able to create the car_database but when i connected it and expanded the node its not similar to whats in this image

http://netbeans.org/images_www/articles/60/java/gui-db/services-db-node.jpg

There are many schemas like APP, NULLID, SQLJ etc.
Which should be the default schema?

I selected the APP as the default schema and created the table and filled the data as told in the tutorial

Now comes the second trouble

I created a new project and did everything as told in the tutorial and when i came to the step of selecting my database, i selected

jdbc:derby://localhost:1527/car_database[nbuser on NBUSER]

and it was shown that the database contains no tables.

But i am able to query the database and i can see values

I have no clue(as is always with noobs) whats wrong

Please help

Also please tell me which is easier(I am new to Java Development and all three of these) to learn and program
JavaDD or MySQL or PostgreSQL?