i'm sorry if this was already explained in the page I did read it I swear
Go to the Discord server, visit the #join channel, and click on the Join the Secret Santa button. A Discord bot is used for managing the secret Santa part of the jam. It will assign Santas to all the participants, and allow you to anonymously communicate with your giftee.
At the end of the jam the bot will send the game your Santa made for you to you.
You can make it public, it's written in the rules you can. Also, you need to have discord to submit your game. Just join the discord: https://discord.gg/tg7KBvfTG