Click the flag until you can see the play button. Instructions are in-game, but you must pick your shift, (1 = day, 2 = night) pick your character, (it will take a few clicks, be patient) and clean off as much dirt as you can using your joystick. Afterwards, you can upgrade your power washer using the money you earned from washing with it!
Thank you @LegoBuzz5697 for giving me permission