You have to add your own sprite. Add code that will allow you to control the sprite. The sprite has to move from the blue start block to the black finish line. If the sprite touches green, something should happen and an appropriate message should display. What will happen when the sprite reaches the finish line? You need to decide. Add another level to your game - if it reaches the finish line in Level 1, change backdrop and create Level 2. Level 2 needs to be harder than Level 1.
Things to think about: How do you get it to always start with the 1st back drop, how do you get your sprite to start in the correct position when you change to the next backdrop, how can you add extra challenges on Level 2, etc.