Video game development entails much more than just programming the game; you have to create the artwork/models, compose the music, design and balance the game, and so on and so forth. Doing all of that
well can be very difficult and time-consuming. This may seem obvious now, but I just wanted to make this clear, in case you had large ambitions for your game. It's better to smart small, then gradually crawl your way upwards to creating bigger and better games.
If you're just starting out in UE4, I'd recommend
looking at these video tutorials first before even considering making a game of your own. It's best to know how to use the engine in the first place, so that when the time comes to actually make your game, you have full command of the engine and won't waste time figuring random shit out.
Also, if you're aiming to a 2D game, I'd recommend something like Unity or GameMaker Studio over UE4. Not that UE4 is bad for it, but, IIRC, it's not really designed for 2D Game Development.
Another way to get your feet wet is to create mods for existing games out there; that way, you can gain experience with asset creation and level design before moving on to creating an entire game from scratch.
Perhaps the most important thing, though, is to not be intimidated. The worst thing you can do is keep second-guessing yourself, resulting you in going nowhere development-wise. Like what Halo said, your first 10 games are going to suck, but just accept that fact and push forward in developing them and getting them out there; you'll learn a lot in the process.