See
my reply to your other post in this forum for advice on switching to a simpler platform for learning Oracle..
You really need to stop and think about what you are trying to do, and what an error message means. The "Insufficient privileges" error means exactly what it says: you have tried to perform an action (creating a table) for which you do not have the necessary privileges.
It's easy to search on Google for the error code, for example, and the error message tells you exactly what you've done wrong in this case, so you should be able to fix this yourself with a little research and thought. For example, I did a quick Google search and found
this video on how to set the privileges for your user via SQL Developer.
Start with one of the many introductory tutorials for Oracle and work through it properly, so you can learn the basics in a more structured fashion before you start trying to build your own application.