The Fornells Bay is the best bay in menorca for windsurfing. At least for the beginners. The winds are not too rough and bay provides shelter from the bigger waves.
At the marker location, there is a windsurfing school called Wind Fornells. The waters around the surfing school are really good for learning surfing as they are shallow enough so students can stand in the water but deep enough so that surfing is possible.
If you are into windsurfing, this is the best place to start it in Menorca. This place is however not suitable for kitesurfing if that is your passion.
There are also SUP and sailing lessons and rentals available.
Easiest by own/rental car. There is a parking lot next to the surfing school.
One teaching session is from about 60€ to 89€ depending how many lessons you will take and if you will book together with someone or alone.
The rental price of windsurf equipment is 53€ for two hours but discount is given if you take more hours/days.