Just released Japanese language learning app, now I need to market it. Suggestions? nihongo.rocks

Hi IH, new here. I've just released a beta of my new product, a web app that helps you learn Japanese and the Japanese characters, Kanji.

I've never really delved into marketing before and I'm not really sure where to start. I put up a post on a small subreddit, but I only got a handful of signups and none of them continued to use the product. I chose a small one so that my competitor wouldn't see, as I believe I have a much smoother, sleeker experience and I don't want them to copy it. Side question: Is that something I even need to be worrying about?

I don't really have money to spend. My current target is people who are learning japanese, particularly people who are studying the standardized test, JLPT.