Adding events to the timeline is simple, especially if you have used WordPress before.
The next page provides the dialogues to add the title and text of the event, choose the feature image for the event, select the appropriate category and then submit it for review!
A reviewer will assess your event and publish it if it fits with the timeline criteria.
To add the date information click on the right and change the date published to the date of the event. It will say whatever date you originally created the event.
To see a picture on the timeline or in your preview you must set the featured image. It will only show up if you make it the featured image. On the bottom right of the add post page there is something that says featured image. Click on that. Then when it brings up the box navigate to the picture you want to add. If you go to the gallery hit show and you will get the details for the picture, a place to put a caption, description, etc. And a place to make it the featured image. Click use as featured image next to insert into post. It will say saving and then say done, you should be set then. You can make multiple pictures the featured images and then they insert in as a gallery.