The coins randomly appear on the screen when you are playing, and when you touch them, you gain the amount said on the coin, and can see how much you have collected at the top left of the screen. Hold down 'Space Bar' to go up, because the character will constantly fall down. Hold down the 'S' key to open the shop (on the top left of the screen) and when you have enough of the money (or more) you can click on one of the upgrades, it tells you how many coins you need for it.
