The instructions are explained in-game. Try not to put flowers by the dragon, because they will go underneath the dragon.
I wanted to make something for the Green Studio, so I decided to make a program with a dragon (since I love dragons) and trash picking up (since it's important to save the environment), so here it is! AAAHHHH!!!!!!! OVER 100 VIEWS?!?!?! Fixed! Now the trash is easier to pick up! SAVE THE EARTH!