I’m writing a persuasive essay….?

I’m writing a persuasive essay….?
My teacher says I need to have a reason to persuade the cause by giving the reader the impression that I know what I’m talking about.

However, in my essay, I am trying to persuade that immigrants are good for the economy and society – but I’m not an immigrant.

How can I establish my grounds behind by cause? Thanks!

He is right. When you write a persuasive essay you have got to be like a lawyer defending your case in front of jury. You make a stand “for” or “against” and write the best possible argument to win over the reader. It is not just for the reader to think “Yes, he has a point”, it is to be “I support this, he is completely right!”.
I do a lot of persuasive essays, and there are couple of things that help me the most.
Open your essay (introduction) with crazy fact/statistic because you need a “hook” to get your reader interested.
Do the Prewriting. Choose a side and then RESEARCH. Everything is about the research. You need to have a proof. If I was you, I would interview some of the immigrants and ask about their finance situation -if it is good then they are helping the State with taxes, jobs….If not-there is your counterclaim.
Talking about the counterclaim, every good paper has an opposing view. You have to make a counterclaim and DEFEAT IT. Take one of the immigrants answer, put it out there, and then defeat with facts OR someone else’s answer. If you have both, it would be better, BUT if not it is OKAY. One is enough.
Each paragraph shall cover separate point, you don’t want to overwhelm the essay with many information in one paragraph.
At the conclusion, teachers always say ”restate your thesis”. NO. You have to encourage the reader to take the position you are taking. Say something strong that will back up everything you have said. Revise it and fix the grammar errors: If it is a good essay, errors will ruin it.

Hope this helps,