when you press the green flag, you will see a blank screen apart from a variable slider in the top left. dragging the slider to 0, setting it to wall will allow you to place a wall when you left click dragging the slider to 1 will switch to water where you can place water down, sadly, you can't pause the game unless you have scratch addons (you can download it on (I'm pretty sure) on chrome web store) (and you can't edit in pause mode) dragging the slider to 2 sets you to erase mode and you can erase stuff
