Ends of pipes arise in front of you. A green and a red dissociate screen, because they are respectively the starting and arrival pipes of the course. Therefore, you will have included/understood it, it is necessary to click on the blue boxes so that the ends of pipes which they contain form a course until the arrival. But that will not be done immediately. As of the beginning, remove the pipes already placed, because they are useless. Then, after having clicked on a box, if it is not the pipe of your choice, click (in the column of right-hand side) on a pipe framed of purple to change it with your own way (or use the key ??), or then entirely erase the column of pipes using the Bar Spaces. In short, it is a good small headache which I would have tried to explain you, and who will give you wire with retordre? Good luck, and try to keep your intact hair!