Hello, jams will appear on the https://itch.io/jams page generally. We also send out email notifications for the top jams, along with sharing on our social media accounts. The jams we like to promote are ones that show effort put into their creation. Take time to fill in details about your jam and why people should join. You should be able to get a few people you already know to join your jam. We're less likely to promote jams with zero participants, since it typically means the creator didn't put in effort to get people to join. Additionally, people browsing for jams on itch.io typically want to join something with other participants.
Thanks