You've received single merit which means you already have a hint of how do we earn merits. The typical way of earning merit is to provide informative and quality posts, like the usual way in content creation, create content and earn like, upvotes and views.

That 1 merit of yours shows that even you aren't doing what we've suggested, you can gain merits but it's not guaranteed since only a few people give it like that. Yeah, it's true that you shouldn't focus on merits because the forum was typically made and focused on pure discussion. I guess it's fine that you should do it for the merits since the forum will also benefit from that, it will lessen spam posting.