To save your progress within the application, click the save button in the top right corner of the application and save your prototype progress as a JSON. You can then import that JSON file to bring back your progress and the application will repopulate the canvas.
To export the project prototype, first click on the "Export" button in the top right corner. Click either "Your Project" to export a full project with boilerplate or click "Active Component" to export the specific component you created in the canvas.