Welcome! I recommend using the communities tab on https://lemmyverse.net/ to find communities that you're interested in. For instance there are multiple communities devoted to world news, but each may have a different political leaning. So in lemmyverse click on the link that starts with an exclamation point. Copy and paste it into the search box here on discuss.tchncs.de then click subscribe. Different communities have different topics of conversation. Don't be afraid to subscribe to different communities on the same topic.
This confused me when I first started, because you won't be logged in on other instances (servers of lemmy) if you click links that people post to other communities.
Sorry if this is a little long. Good luck and welcome!