I’m assuming this is for an English essay?
So, the thesis will come at the end of your introduction paragraph / lead. The lead is basically you getting the reader’s attention, and the thesis is the main idea. It is what you will argue or explain in your essay, so make sure you are clear about your position, and give the reasons why. Make sure these are clear enough that can give supporting details in the rest of the essay.
Basically, a thesis statement is your opinion, but state it as a fact. And avoid using personal pronouns (I, you, we/us, they). This will make it seem more like a fact.
I hope this helped!