AppyBuilder (as an instance of App Inventor) is a really cool and easy to use tool, especially for a beginner. I’ve never before published an app anywhere (though I took some introductory level programming courses 25 years ago, and have some practical experience with “scripting” in Perl), and I already have two fully finished apps published via Google Play (and soon into the Amazon AppStore as well).
I encourage you to simply walk through a few of the introductory tutorials, they’re very “hands on” (which I appreciate) and see how easy it is to translate what’s in your head into a bonafide app! The AppyBuilder community is also very encouraging and supportive. If you get stuck at any point, people are more than willing to point you in the right direction for answers.