I can give you some feedback to help you improve the essay yourself. The first thing you must do is establish basic competence in English while stating your thesis. As it stands, the essay begins with two extremely long run on sentences:
There are some important advantages of capital punishment, and why the capital punishment is a good way to punish the people, and the advantages of capital punishment.
Capital punishment is an important way to punish the criminals, who killed people or who slaughters people because they killed people, so depend on their criminals, they deserve the capital punishment.
I think that the first sentence could end where you have the first comma. The second sentence becomes incoherent by the clause "so depend on their criminals." Since I can't figure out what you are saying, I can't suggest how to rephrase it. Start again, using very short, simple sentences.