I'm sorry I don't speak German but I can try to translate things if you have questions
There is also lots of help for new people on the website at https://fedi.tips (especially Quick Start at the top of the page).
@FediTips
I am looking for some insights for using the different timelines and posting to them. And the effect it has depending on the kind of followers.
There is a guide to different timelines here:
You don't specifically post to them, your posts will automatically appear (or not) depending on which visibility settings you use for your post:
https://fedi.tips/who-can-see-my-posts-in-mastodon-how-do-i-send-dms-in-mastodon