It is very important to save your work often! Otherwise, you might lose something important.
To save a new project in Scratch, click on File and then Save as (Save Project for Chromebooks using ScratchX). Give your project a name and then click Save. Once your project has a name, you can save it by going to File and then Save.
DO NOT name your Scratch file HummingbirdStart. This will overwrite the blank file that should appear when you open Scratch from the Birdbrain Robot Server.
See https://www.birdbraintechnologies.com/hummingbirdduo/scratch/program/#saving for up to-date instructions on the Birdbrain Technologies website.