Did you mean your question about Lumiose City style? If so, then that was waiting for approval; it wasn't hidden. I've approved it, you can find it here.
If you ever think that your question or answer was hidden wrongfully, then you can ask about it by leaving an answer here. The person who hid it (or somebody else who knows) will hopefully explain to you why they hid it. Of course, don't post there if it hasn't been shown after something like 15 minutes, because it is probably still waiting for approval.
A possibility is that you think your questions have been hidden, but they haven't. You can find a list of your questions here, so if a question you asked isn't there, assume that it was hidden or it is still waiting for approval.
Once you have 30 points (correct me if that number is wrong), you can bypass the approval system entirely. 30 points is pretty easy to get considering you start off with 20; a simple upvote will get you there, so yeah :)