When you are writing an argumentative or persuasive essay, you have a position you are advocating. For example, you might take a position on capital punishment. You might inform your audience that you oppose capital punishment. That is the thesis for your essay.
But is it enough to tell your audience you oppose capital punishment and not say any more? Of course not! No reader is going to change his or her mind on just your say so. You need to support your position. How you support your position depends on the subject you are discussing and the position you take. Each time you write an argumentative or persuasive essay, there will be different kinds of evidence.
What kinds of evidence are available to you? You can discuss specific incidents that you know about or discover through your research. We call that anecdotal evidence. If you were writing an essay arguing that capital punishment should be abolished, you might present a story about people who were found to be innocent after they were executed. You can present statistics to support your thesis. That is called statistical evidence. For example, the statistics might show that capital punishment does not decrease crime. Sometimes you can use a hypothetical situation to make your case or use logic. We can also use visuals to support a position, for example, a picture or a graph.
Since I do not know what topic or position you are going to write about, I cannot give you examples that will help your specific situation. But I do hope that this helps you to see the kind of evidence you need to support a position.
Good luck to you.