When creating a website you choose which hashtags to show - it's not only about navigation, it's about what content is shown on the site. 

Main page shows everything you've selected (all hashtags you've chosen) by default, but you can choose specific hashtags for homepage in settings.

Whenever you post something with selected hashtags it appears on the website. 

And "long form posts" are posts you can make using habla.news or highlighter.com - they have title, summary, and allow for formatting (links, lists, subtitles etc). 

Let me know if you have any more questions or feedback, thank!