Thank you so much for your reply! I realize my own reply is a bit late, but that is because the link you have sent me has worked wonders so far.  It starts from the very beginning and shows everything step by step without assuming you know a lot already, and that turned out to be exactly what I needed.
I have now managed to get a dummy network running (though I’m still figuring out how to display its results, but it runs over my training data at the very least!). I’m now going to work on retrieving the output so I can see what it actually does. And I’ll still have to incorporate validation data, too. I’m no doubt going to run into more issues further down the line, but I can post them in this thread if I get stuck again.
For the time being, I just wanted to thank you and let you know that the link has really helped!