Where I can find a good Esperanto course for Spanish speakers?
Duolingo, the language learning website, has one currently in beta. The course will be rather brief due to its newness, but if it's like the English course it should cover most of the essentials. They have both a website and a phone application.
Kurso de Esperanto is a freely available computer program for learning Esperanto. It's available in a lot of languages, including Spanish. I haven't used it, so I can't say how good it is.
A very good place if not THE BEST is lernu.net. You'll find adaptations of courses like Ana Pana to complete them fully online with a teacher who corrects your exercises and who will help you with any doubts you might have all FOR FREE. From beginner to advanced!
Unfortunately, they no longer have the correspondence exercises since the relaunch. The Ana Pana courses and others are available in the Lernu library, but only for reading/listening, no correspondence. They have put the focus on a single longer course that has some interactivity but no correspondence with actual teachers.– kristanOct 27, 2016 at 2:12