@fallandegubbe this is a great project to learn how to code, and JavaScript is quite a forgiving language, so it’s perfect for beginners. What you’ll need to do is pretty straightforward and common for MM modules.
First search for an online JavaScript 101… plenty of free resources available. Then download and examine the code for an existing module as a template to get an idea what the structure looks like. Finally do a bit of Googling to learn how to do specific things like make an AJAX for API data, and how to programmatically create HTML markup.
Try to keep it simple from the get go. You can accomplish what you want to do without anything fancy like a Node helper File or even an external CSS file. Once you have a working module (which will quite a satisfying accomplishment — congrats for sticking with it!) you can make improvements in order to learn some of the more advanced stuff.
You can do this! Speaking as someone who does not code for a living, nor would I consider myself a “programmer,” I can confidently say that you can learn everything you need with a couple days effort and liberal Googling, a dash of determination to stick with it. Also, this forum is a great place to ask questions when you get stuck. Lots of us got started in the exact same way.
Once you’ve finished your module, you can get the fancy “Module Developer” badge beside your name too!