Add Author or Role to Posts

Hi there,
I’ve been searching to try and find this but haven’t been able to figure it out so I’m hoping someone has an easy answer! One of the themes I was using would title the post, have the date, and then Posted by ‘Author’ or ‘Role’. We have several users that will be posting in our blog and I want people to be able to see who is posting what.

I am using a different theme now but they don’t list the Author on the posts. I’ve tried sifting through the other theme to find the line that I need to add, but haven’t figured it out yet.

Is there a simple line that I need to add to show the Author of the post in the Theme Presentation somewhere?

Thanks in advance!