When structuring an argument, where should the thesis statement be placed ? ?

In an argumentative essay, a thesis statement is a claim.

It is found in the introductory paragraph.

Because it is a claim, the thesis statement should be clear and assertive in tone and nature. The paragraphs following said claim will then be written in support of the claim. Facts and other information will be stated to persuade readers and convince them to share the same view as the writer.