How can I get Ruby to save things, so that the next time I open the program it will still be there? (As in, when I update it, how can I get what I have changed to still be the same when I display it.)
You can't do that without a way to store data somewhere, whether it's in a file or in a database, and this is only an environment to learn basic code, so you won't have that. But feel free to start coding on your computer and you'll be able to, for example, store a list in a file and then modify this file any time you want with your program. You'll need to explore some more on Ruby though, because this course doesn't cover file manipulation.
Would I learn that sort of thing on the 'Ruby on Rails' courses?