There are different ways to promote the website. You can go with SEO (Search Engine Optimization), yes this is a very useful way to promoting the website. On the other hand, you can also go with pay marketing like like Facebook Ads, Google Ads, etc.
SEO is a good medium but i will suggest you to try social media for this process. Facebook, Twitter, Reddit etc are good for these kind of websites. If you can spend some money on social media, then it will be more effective for your website.