The thesis statement is simply the sentence in which the author states the argument which the remainder of the essay will support. The thesis needs to clearly state your position on the topic.
For the purpose of this class, the thesis will almost always be a restatement of the question and your answer. For instance, if the topic question were:
What is the most important piece of advice you have ever received? Discuss.
Your thesis would be something along these lines:
The most important piece of advice I have ever received was when my Grandfather told me to "never stop learning."
The thesis may be combined with the preview to form a complex sentence.