This isn't a supported feature and I wouldn't recommend making these modifications unless you feel you are comfortable with php and sql.
There are a few things you will have to add, one being an entry in the database for the new content area. You can look at the way the others are added in the ps3_contents table. You don't have to add anything for the ps3_contenthistory table. That will be updated as the content areas are modified.
You will also have to add the includes at the top of the page for the globals, connection and cms. You will then have to add the cms content area code that should look similar to this:
echo WA_getCMSContent($database_PowerStoreConnection, $PowerStoreConnection, 'About Us' , 'Company Info');
the 'About Us' and 'Company Info' will be changed based on the values you entered into the database.