It's been too long since I've been a beginner, and things have changed. Maybe the official Python tutorial, or the Invent With Python books? But since you're using Twine already, learn the more advanced features of your preferred story format, like loops, conditionals, variables, arrays... that alone is going to teach you a lot. SugarCube markup in particular is as powerful as any programming language, but I think Harlowe isn't far behind.