If you want to get free kitesurfing lessons you should check where is going to take place the next kitesurfing instructor course and volunteer as student. Click here to check the dates and join them. Usually the second and third day of the kitesurfing instructor course would be the days that you would get the free lessons. But I recomend you to call directly to the kitesurfing school and tell them that you want to volunteer as a kitesurfing student.
Enjoy your free kitesurfing lessons!