If you want to quickly try out the new features after installing APEX 4.0 you don't need to do anything! APEX now comes with a built in demo.
To access this demo, log into a workspace and click the "Learn more..." button.
On the right hand side you'll see a list of features to demo.
If you're curious, the tables that the demo is using are: APEX_040000.WWV_DEMO_DEPT and APEX_040000.WWV_DEMO_EMP.