See the area that says:
This editor uses Markdown syntax, which makes it easy to add formatting like italics, bold, and lists:
https://duckduckgo.com
https://google.com
https://bing.comPreview this post to see the results.
For more details, see this Markdown demo.
You need to click inside, the text will dissappear and you can write your post. Then click on “post your reply”.