You have accidentally crossed the last line and entered the forest. There is no turning back from the place you are in. You will have to go deeper into the forest and unlock the final portal to escape from the forest. However, that is not the only portal that you will have to unlock. There are more portals and each portal is a gateway to another location. So there is no choice but to unlock each portal that you come across while exploring the forest. As you look around carefully you will find odd things that you must pick up and use intelligently.