I have an idea for a video game where do I start?

I only know Qbasic but am willing to learn. Will be a text only game to start. No music or graphics to start. Only logic like a choose your own adventure novel? Where can I start? Or should I make a flowchart? I want to make a character generator from lv zero to level 1 as a game. Where you start as a young child to level 1.