hello! this is probably a veryyyy late response and you might have gotten some sort of an idea from your teacher - but I'm doing my HSC this year so maybe I can provide some help for the future
the way I usually structure my ext intro is:
thesis.
then a kind of elaboration on my thesis.
then I state each text with its context in like a seperate line so for example:
"Mary Shelley's gothic novel 'Frankenstein' utilises the turbulent transition from the Romantic period to the Enlightenment in order to convey the nature of religious and scientific upheaval. On the other hand 'Text 2' does blah blah blah. Consequently, 'text 3' does yap yap yap. Finally, 'text 4' does yadayadayada.
And then my final sentence is a bit of a concluding sentence to link back to my thesis.
Hope that helps!