I think you are a little late to promote this site as it one of the most famous faucets... It will be difficult to attract new users.
How to get referrals? Share your link on blogs, websites, videos, forums, twitter, facebook, ...
Because there are already many FreeBitcoin users at this time, I even played a faucet at the time when I got a bigger satoshi, but now we are betting more on the numbers we set and try our luck with the jackpot every time we announce it.
Well if you are still curious about sharing references, you can use social media or introduce to your friends who like to gamble, maybe that's more appropriate.
FreeBitcoin is one of the longest running faucets I've known to date.
In the past I used to visit many online money making forums where I used to interact with like minded people, and slowly and steadily I build my referral list but this method is saturated in 2020. However don’t loose hope you can yet make a crypto related blog, and write about ways to earn free bitcoins and put up Freebitco affiliate links, and add banners on your site and then work on growing it. Lastly you can even try paid shoutouts from crypto influencers who have a decent fan following, as that would help you build a decent referral list in the long run if you continuously purchase those shoutouts.