Arrow keys / WASD (or the on-screen controls) to move + rotate, Down to soft-drop, Space to hard-drop, C (or Shift, or Hold) to swap the current piece into hold - once per piece. Every shape has its own colour and always will - pick a palette from the "Blocks" dropdown and it is remembered next time. The glowing background reacts live to your moves, drops, rotations, and line clears - pick a different one from the "Background" dropdown any time, or switch "Effects" off to disable it completely.