Your topic is, "Hester -- did she get more than she deserved?"
I assume you mean: did she get more punishment than she deserved.
Obviously, you must first decide if you want to argue "yes" or "no." I'll give you a few points on each side.
"Yes" (she was overly punished):
a) Her sin took only a few minutes, but her punishment lasted a lifetime.
b) Since she was not living with her husband at the time of her relationship with Dimmesdale, her adultery was only technical.
c) She had to observe and suffer the way her child, who did not sin at all, was rejected and belittled by all the other children.
"No" (her punishment was not excessive):
a) The Puritans followed the Bible, and the Biblical punishment for adultery is death. By not putting Hester to death, the community was being kind and merciful.
b) Hester could have made things much easier for herself if she had identified the man who had sinned with her. She refused of her own free will and suffered the consequences.
c) Hester never formally apologized to the community for the shame that she brought upon them. So, one can't blame the community for being a little harsh on her.
Each argument that you use should be developed into a complete paragraph. Be sure to be very specific and to use some short quotations from the text.
A good general rule is to think about your audience. Although your teacher is probably the main person who will read your paper, it is best not to think of him or her as your audience. Since you know that the teacher knows the story quite well, you will tend to tell very little in your paper if you consider your teacher to be your audience.
Instead, do what I used to tell my elementary-school students: Your audience is your grandma! Your grandma probably never read The Scarlet Letter, and if she did, it was probably a long time ago. So go ahead and explain, explain, explain!
Writing good papers takes practice. I always find that is easier to start with an outline. Having a well thought out outline will help get the wheels turning and will make the process of writing the paper flow more smoothly.
You want to introduce the reader to what it is they are about to read. Just give them a general overview of the topic-nothing too detailed. You may also want to add some flare to the introduction in order to get their attention and interest.
You will continue with the body of the paper. This is where you will discuss specific topics in detail.
The ending of course is the conclusion. Here you will want to sum up the entire paper. Again, no detail but you will want to wrap everything up so there are no loose ends.
If you are giving a presentation it is a good idea to ask your audience if they have any questions.