If you recently learned the basics: Dive in and experiment with the possibilities of the software. Just hack a improvised game together with the stock assets.
Then, if you feel comfortable with the software go over to plan your game. Make something small as your first game. Write a short story, and make a small list with the most important characters and places, create them in your engine and try to build the game using these. If you have the rudimentary things, look if something is missing and add it if needed.
Back when I used it, the RPG Maker had some good included assets - if this is still true, try to rely on them. You save a lot of work, and getting a small game done should be your first priority. If you have more routine and an idea what to do you can start to make more ambitious projects.