Zorba's Ranch, Milatos, Tel Esther 0030 6945 333639 (mobile), probably about €15 - €20 by taxi from Stalis. They cater for beginers with no experience to experienced riders. If you are the later you can rent a horse for the day and go and explore. they also have a riding school, which my wife attended last year and enjoyed, apart from the pain!!! The horses are well looked after, the owner is Dutch.
keith