Move your mouse/finger to guide the creature to the end of the path. If you touch the goldish-orange color (which is the end) then you'll move on to the next level. If you accidentally touch the peach color, no worries. You can just go back to the start and start over. Watch out for the enemy in level 3! In level 4, you need to get on the green platform to get to the other side.
CodaKid gave me interesting thoughts on how to create a new project. All of it was my work.