|Your homework should serve the purpose that you learn something. And that something isn't supposed to be how to get other people to doing your homework for you.
Your assignments will get more difficult over time - so if you don't start doing them yourself now you'll never be able to.
So sit down, think about it and try something. If you then encounter a specific problem, feel free to ask - that's the idea of these forums.
Also, there are a lot of articles here on CodeProject about expression evaluation. Take a look at those if you struggle to find a starting point.
If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson