First, take a look at the posts in the "introduceyourself" category (new,Trending) to get an idea what to put in your own. This is social media, so rewards come from interacting with other people. That's how the steemit community learns about new members.

Next, you'll want to get some followers. If no one's following you, your posts won't get seen, so they won't be rewarded. The best way to get followers is to Reply and Up-vote on other people's posts, with meaningful, relevant, authentic comments.

If you do those things, and post your own content regularly, you'll see your earnings start to grow.

Also, it takes a post 7 days to pay out. During that time, you may see the value go up and down because it's only a "potential payout." Whatever a post earns will show up in your wallet 7 days after you post. It's only been 3 days since your first post, so if it had earnings, they still wouldn't appear in your wallet for another 4 days.