To send an MMS using Node.js and Twilio, start by creating a new project directory, initializing a new Node.js app, installing the required dependencies, buying a Twilio phone number, and setting up environment variables for your Twilio account credentials. Then, create a file named index.js to send an MMS with media content, replacing the placeholders with your actual credentials. Finally, run the application with the command `node index.js` to receive the sent message on your personal phone.