You can get started by checking out the XMTP developer resources, specifically: 

Developer Resources

• 💻 XMTP Developer Docs - https://docs.xmtp.org 
• 🐙XMTP JS SDK - https://github.com/xmtp/xmtp-js
• 🐙XMTP Example Chat App - https://github.com/xmtp/example-chat-react

Previous Hackathon Project Examples

• 💻Message-based Bartering System with OpenSea + XMTP - https://github.com/Aqrare/eth-nyc
• 💻E2EE chats through an Intercom-type widget for NFT merchants - https://github.com/openmagic-io/openmagic-community-marketplace-demo
• 💻Token-gated chat with XMTP + Lit Protocol - https://github.com/NftTopBest/example-chat-react-gitcoin-hackathon 
• 💻Connection-gated Chat with XTMP + CyberConnect - https://github.com/thedarkrai07/cyberconnect-xmtp-1 
• ▶️Example Demo Video of Connection Gated Chat - https://www.youtube.com/watch?v=ns02CxG63YU
• ▶️Example Demo Video of Token-gated chat - https://www.youtube.com/watch?v=QTd6Cz9Ak_U 

Helpful UI Examples

• DAOPanel (Conversation UI on top of XMTP)
• https://github.com/daopanel/hello  

Connect with Us

• 👾Official Discord Access - https://xmtp.typeform.com/early-access
• 🐦XMTP Official Twitter - https://twitter.com/xmtp_ 
• 🌐XMTP Website - https://xmtp.com/
• 📖XMTP Labs Jobs - https://blog.xmtp.com/careers/