It's very simple − keep completing the tasks on the left part of the screen and follow the hints.
During the tutorial, you can do only the actions the game asks you to do. It was made with the intention to show the basic principles of the game, how it works and what you can do. This information will show you how to progress further.
The tutorial is quite short. In level three you will already have the opportunity to move more freely on the island, and by level five you will be completely on your own, ready for the big adventures. You will be free to explore before you know it.