How it works
A sprite is a character on the stage, and blocks tell it what to do. It does nothing by itself.
A stack of blocks runs from the top to the bottom, one block at a time.
An event block, like the flag, says when the stack starts.
Each block has one job: go to puts the sprite on a spot, move walks it, turn changes the way it faces, say makes a speech bubble, and wait pauses.