score:4
How should I write that in the form?
Should I write every country that I visited in Europe?
or should I just write Europe?
Neither Europe nor the Schengen Area are countries. You will need to list out every single country in the Schengen Area you have visited in the form.
And how do I extend the form?
The final page in Australian immigration forms usually provides room for additional information (sample below). Use this field to provide the additional information required, and reference the question number.