@shiratorii welcome aboard!

I never used social network, before joining either, but got used to it fast. As for gaining content to garnish your feed, start following people, even if there is a minor overlap in your interest. You can unfollow later, no worries (people won't get notified if you unfollow them). Search for hashtags around your interests and hobbies and follow those too. Look at the federated timeline – lots of stuff happening over there. It will take a few days to properly kickstart your feed.