DON'T start any paper's first draft by writing the introduction! How can you introduce a paper that you haven't written yet?
Follow the writing process, whether you're writing for science, history, English, or whatever:
Prewriting: Brainstorm, research, plan, outline, thesis statement
Writing: Write first draft by starting with section II of your outline; write the introduction after the body of the paper is written; write the conclusion last.
Polishing: Revise, concentrating first on the body of the paper, then the intro, then the concl (revision = making sure ideas are logical and sequential and support your thesis); proofread (spelling, grammar, usage, etc.)
Do you have a thesis yet? Have you done your brainstorming (and maybe research) yet? Have you written an outline?
Click on Step by Step for the process. Click on Info Search for help with researching.
Check in the Essay & Research Paper Level.
Your thesis statement must include factual information (which you may already have if you have begun your research) plus your position/opinion/stance. Without your position on the topic, it isn't a true thesis statement. So think of this sentence as the angle you want to take on the topic and what you intend to prove by the end of your paper. (If your statement is simply factual, then there's nothing to prove!)
This is one of the very best places I've seen online to help students write good thesis statements. It shows you sentences that aren't thesis statements and how to turn each one into real thesis statements.