What Needs to Happen to Put a Game on Steam?

So my friends and I are making a game. I’ve made a game function through LAN, but we live across the country, so this game needs Online play. From my web searches, going through Steam is the easier way to connect online. Something about ports or running servers, I’m still new to all of this.

So what I want to figure out is A): What additional things do I need to do on the Blueprint side of things? B): What does the Online Subsystem Steam plugin do when I enable it? C): What needs to happen outside of Unreal Engine?

I’ve looked around the internet and I’m having a tough time tying all the answers together.