In order to do this, you'll need to be able to install plug-ins on your WordPress account. If you are using a free WordPress account this won't be possible. Furthermore, if you are hosting your site or blog on WordPress, you'll need to purchase the top hosting package in order to install the plug-ins for your site. Otherwise, you'll need to host your WordPress account with a different hosting company. Install the WordPress plug-in called Co-Authors Plus. Edit the post or page where you want to install a different author or other authors. You'll need to do this in your dashboard under WP Admin. Now you can see the authors box on the edit screen. In this box, you can now add another author or change the author. Type in the name and you'll find the different names of the authors as you type. Select the one you want to add.