New person, it works pretty simple. There's, like, three ways you can go about it, depending on what it is that actually appeals to you.
1. The Adventure Continues!: Simply put, maybe the reason you want to write Star Wars is pretty simply because the adventures, Luke, Leia, Han and Chewie going off and doing shit, was what you loved. Thus, given how the story ends, it's pretty easy to just do a continuation of their tale, a sort of "What happened between Return of the Jedi and Force Awakens?" There was still a huge Empire to be destroyed, and the gang and the rebels, or new republic, or whatever, would've still had a lot of shit to do after Endor. Thus, you could set your story there, like Star Wars Battlefront II did.
2. Exploring Hidden Depths: Maybe you like the parameters of the story, but want a bit more freedom than working with the cast. So, you can expand on the mindsets of characters we haven't dealt with. This has been done to shit by the Expanded Universe, but whatever. We have endless cool characters in Star Wars who weren't expanded on in the film, be it the Bounty Hunters, those in Jabba's or wherever. You could easily expand on the thoughts and feelings of one of those characters, and there perspectives of things. You could explore one of Vader's personal stormtroopers marching with him onto the Tantive-IV, seeing what we saw as heroes being gunned down instead as akin to a military force wiping out a terrorist cell.
3. The Universe is Your Oyster: This one's my favorite. Maybe you like the Star Wars universe, but you want freedom to write. So, simply set the story in the Star Wars world, and do whatever the hell you want. Really, any type of story can fit in a Star Wars realm. A heist story of smugglers trying to rob Moff Tarkin's personal treasures. A gangster story of a Hutt Money Man rising to power. A war story of beaten down clone troopers trying to hold off against endless foes. A monster movie of a bizarre alien terrorizing a town. Take the universe Star Wars is set in, and make it your playground. Write whatever story you want in the realm.