what you must do: 1. go into the "Chart" sprite. 2. use the timer sprite as a way of waiting. 3. use "create clone of" blocks to create arrows. 4. switch the costumes of the main sprite (not a clone) before cloning it for your chart. 5 (optional). switch the theme of the game! change the costumes of the characters, change the arrows, change the icons and health bar, create different notes, change even the background. boom there you go an entire mod ig (note: you MUST have a song.)
y'know that other chart creator? i made it low quality so that it isn't that hard for you. :)