As Marion Cushman of Los Angeles City College Library notes, a thesis statement is a single, clear, complete sentence that states the main idea of the piece being outlined. The most common mistake with a thesis statement is not writing a complete sentence. "The death penalty" is not a thesis statement. "It would be less expensive to abolish the death penalty than to keep it" is an adequate thesis statement. The main points of the essay or speech would then be to present arguments about why doing away with the death penalty would save money.
The main points are the points that argue for what is stated in the thesis statement, or that elaborate upon the thesis statement. For the article you are reading, the last sentence in the first paragraph is the thesis statement. Points mentioned in that thesis statement are the main points that are elaborated upon as the article unfolds. Proper outline form calls for using Roman numbers to identify the main points in the outline. The point you are now reading would appear in the written outline as "II. Main Points."
Subordinate points are the points you wish to make that explain or defend the main points. Supporting material varies. It may include quotes from experts, statistics, anecdotes, stories and personal observations. Each subordinate point is listed under its appropriate main point in the outline using capital letters.
In a good outline, the main points are related in a logical fashion. There are a number of kinds of possible logical relationships. Some outlines are chronological because the writer wants to show the development of something over time. Topical outlines work well when there are a number of different arguments to be made for the thesis statement. For example, the death penalty thesis statement mentioned above could lead to an essay in which each main point features one way in which abolishing the death penalty would be an economical thing to do.