I need some tips on how to write an introduction on an essay on a trial.
This is an interesting question because it leads to the heart of the story, which is what happens during the trial itself.
Generally, the first paragraph of an essay reflects the type of essay you have been asked to write--argument/persuasion; comparison-contrast/; description; narration; process--but I will try to give you some ideas for an introduction that can reflect several modes.
One of the best ways to get your reader "hooked," that is, interested enough to keep reading, is to give the reader a clue as to why the trial is important to the overall story. But before telling the reader what your thesis or topic statement is, you might want to choose some critical dialogue from the trial that reflects your thesis. This technique almost guarantees that the reader, who is familiar with the story, will be led further into the essay.
After using an appropriate quote from the trial dialogue, you can then state your thesis about the trial as the last sentence of the introductory paragraph or as the first sentence of the second paragraph. If you are writing an argument essay, for example, articulating your thesis in a single declarative sentence is crucial to the essay's ultimate success, so be sure that the dialogue you choose supports the main point you make in your thesis statement.
If your teacher has instructed you to place the thesis or topic statement at the beginning of the first paragraph, by all means do that. You can then use a quote that supports the thesis in the body of the introductory paragraph, and you will have conformed the essay to the teacher's instructions.