Try to find a venue or if you are comfortable enough, use your house as a venue. Try to find a Facebook or discord page in your area for smashers. If there are none, then make one yourself and advertise a lot.
There is an alex valle interview floating around the internet or youtube and some by others in the fgc community. If you find them it should help you staer your local. Try searching up his name with "how to build/start a scene/community".
As for a competitive smash player, in the general sense you already one. You use this website and you are looking to start a scene and possibly get better. To many people not aware of competitive videogames, you already fit that category to them so you are fine.
Now if you are asking for advice on how to better yourself as a player that is a different question.