Hey Stephanie!
You are in luck, I do know how to do this and it works well. There is a free plugin that I use extensively called WP User Front End. The free version is here: http://wordpress.org/plugins/wp-user-frontend/
There are others but for me this one works so much better and has tons of options including to allow anonymous submissions from visitors to your site. Let me know if you have any questions!
Mike (Castro Boy)
