I've been a self taught designer for as long as I've been a self taught programmer.
Initially I started out building basic 2D games in GameMaker Studio which got me to start to draw pixel art (just basic stuff) so I'd say if you want to make a game maybe start out with that.
In my honest opinion I believe that design is quite mathematical and structure.
Definitely download Figma and do your best to learn the basics - it's an incredibly useful piece of software and on the internet there's plenty of challenges and resources that you'd be able to do to get the skills of Figma.
I remember I did a "30 days of design" challenge a little while ago which sent me an email every day with a concept to design. I'd try and find that and see if it's still up and running.
I wish you the very best with your endeavours! Welcome to the design community <3