|How does the picture tube know where to push the electrons onto the right areas/dots?
The television and picture tube simply scans the electron beam across the screen, one horizontal row after the next as it moves "slowly" down the screen. When it gets to the bottom of the screen, the picture tube brings the beam back to the top of the screen and starts over again. While the TV is scanning the beam across the set, it uses the signal from the television station to control the intensity of the electron beam and those the brightness of the spots on the screen. It also watches for sync information to know when to begin new horizontal lines and vertical sweeps.