How do I write a compare and contrast essay?

How do I write a compare and contrast essay?
I’ve never written one before, let only heard about it until yesterday.

My topic is on the battle of paschendale using Sun Tzu’s Art of War.

How do I start?

You start by saying what, where and when the battle of Passchaendaele was, and what Sun Tzu’s ‘Art of War’ was and when,by whom, and where it was written.
You then look at how Haig, the British commander, planned and ran the battle. Look at what Sun Tzu has to say about planning and running battles.
Then, write about what ways Haig did what Sun Tzu says, and what ways he didn’t.
Personally, I think Haig was an incompetent butcher who should have been removed from army command.
Sun Tzu’s ‘Art of War’ is a famous ancient Chinese treatise on war, but to me it seems full of self evident truths and lacks any real insight or detailed analysis of strategy or tactics.