@areej I just click on their names and then the follow-icon (this is in the web version, I don't know how the apps do it). The easiest I've found is to follow some hashtags like
#seo and just add people as they post there. If you end up clicking on someone and it opens on their instance, you can copy & paste the URL to your search bar, and open it locally to follow them directly (you can also do it through their page, but I find it annoying).