When you are logged in you are per default the author of a new post you create. Why do you think you have to “put yourself” as the author?
If you are an editor on a blog you might change the author in the author metabox on the edit page.
If you need to see the author of a post on the front, this is something your theme, or your theme settings, are responsible for. It might be shown as a byline on top of each post or in a meta section below.