Ethos or ethical appeal, means convincing by the character of the author. We tend to believe people whom we respect. One of the central problems of argumentation is to project an impression to the reader that you are someone worth listening to, in other words making yourself into an author with authority on the subject of the paper, as well as someone who is likable and worthy of respect. This will help to appeal to ethos in writing, as it'll make more people want to read what you write, as you as an author seem to have more credibility of what you're saying in your writing.
I hope this helps.