Get a sponsor from the faculty. Get club approved by whoever approves it. See if your school has availible funding for clubs (probably won't.). Organize dates and times. Advertise.
It depends on the school, but usually, you need a teacher or staff member from your school to be the club host or something. Then you need to get enough people interested in it. That's usually it, but some schools are different.
Get a staff teacher i guess, and organize reunions and advertise.... ALOT of advertisement.... cuz convincing peeps to come solve cubes with you for an evening isnt a very attractive thiing from a mortal's point of view.