When you're signed in, Save puts it in your account, so you can open it on any computer from ▾ → Open Program. A free account keeps 5 programs.
Saving needs a free account: Save asks you to sign in, and your program stays open while you do. Without an account, use ▾ → Download Program File, then ▾ → Open Program File on another computer.
Open Create, start a program, and press Save to see it for yourself.
Try it