You're in the right place! Lots of helpful people here and most of the games you'll find on Itch are relatively simple (compared to their AAA counterparts).
Since you're just beginning, I would start with this video which does a very good job of explaining one of the basic concepts you'll need to understand -- the main game loop.
Once you understand how a game loop works, I would recommend trying a simple game engine, like Scratch, Hyperpad, Construct 3 or Gamemaker. After finding one that is intuitive, try to make a short, simple but classic game that's already been done before. A text adventure, Pong, Tetris, Space Invaders, the first level of Mario, etc. Think of it like learning how to draw by copying something that's already been drawn for you.
After you feel comfortable making a game like those, try and modify them with your own stories and art. Eventually you'll gain the confidence and knowledge where you can start making your own game and come up with your own game mechanics. Game Jams are great for creating small projects and testing their viability.
Most of all just have fun!