Please help i need to know how to go about writing a 5-by-5 essay about this topic, if anyone has any ideas or opinions on how to start and what sites and all to use that would be greatly appreciated.
The central drama of the story does not necessarily relate to American power structures, but the underlying themes can easily be drawn together under this idea. Crooks, Curley's wife and Candy each suffer in isolation that is socially defined and which is dictated essentially by a heirarchy of power.
The powerless are cast out, have no say in things, and develop into rather ugly creatures as a result.
To build on Jaime's fine post, to write the sort of essay you're talking about, you need to look past the personal. By that I mean, what happens to Curley's wife is sad, and what happens to Lennie is tragic. For this to matter to readers as a work of fiction, the story has to evoke sadness from you. However, to work as the sort of social critique you're talking about, you need to look at the characters as individuals—and as representative of larger forces. It doesn't just happen that George and Lennie drift from ranch to ranch; they drift because of the intersection of their personal characters with the larger social forces. You'll want to look at those forces.
Start by asking yourself things like "Where does power come from in this book?"
A frequent theme in Steinbeck's work revolves around the fact that people who produce our food are no longer intimately involved in its production. They miss a connection of personal connection to the land. The personal has become corporate, and this creates an imbalance. Greed becomes the prime movitation rather than pride in one's work. The landowners have replaced men with machines, and often treat the remaining men who work their land for them as machines. Think of poor Candy, who once his worth is used up, he is discarded like a piece of trash.
Another way to go with this topic is to think of the imbalance of power between women and men. Curley's wife is so shadowed by her husband that she is not even given a name of her own.