Include author in post

I am trying to find the code that will include the author in all posts. I have a lot of contributors on my site and want to include the author. My theme is dark night. Also, have two other questions. When you click on comments the setup of my site misconfigures. It turns white instead of black and everything is uncentered. When you refresh, everything straightens up. It also does the same thing when you click a link on the site and then go back in your browser. Also, would like to know how to create links in your posts to go to pages that you created.

Thanks,
Nick