HELP!

here i am sitting in front of the laptop for the past few hours trying to figure out how to write a good introduction for this essay 'Discuss the principles of ethics that you have studied in this unit' that is due on this coming wednesday. squeezed every single juice out of my brain but still nothing came out. damnit. this module is definitely killing me with all their theories. i wonder how's the damn exam going to be like. to make things worst, the lecturer had absolutely no idea what sort of questions we be tested on thus he cant provide us with the much needed tips. my god.