Hello Tafader,
You can add posts by guest contributors by creating a New User account for each author and then either allowing those guest authors to log into the site and create the post themselves or by pasting their text into a New Post and selecting their name in the Author Box.
To create a New User account:
- Log in to your WordPress Administration Panel (Dashboard).
- Click the Users tab.
- Click the Add New Sub Tab.
- Start filling in the blanks to create a New User account.
- Select their Role.
- Finally, when you are ready, click on Add New User.
Now, that User can log in to your WordPress with the username and password you created for them and write posts under their own name.
If you’d prefer to not have Users log in to your Administration Panel, you can paste their text into a New Post and select the User’s name who wrote it in the Author Box which will either be below or to the right of the Post Editing Area. If you don’t see the Author Box, you can enable it by clicking on the Screen Options in the top right corner of the your screen.