The description is useful for making your event easy to understand by your audience.
Add a descriptive/promotional text. You can format it with the toolbar that appears once the word is selected, you can format the text as bold, italic, underlined, you can allign it or insert a link by pasting it directly in the text.
The description needs to be synthetic in order for it to be efficient; if you want to add more text, all you need to do is to select the “Text” button on the lower side of the page, and this will add more space for the extra information.