For INside Espana=Spain?

See renfe.com. NOte that many people comment there are often very long waits and most operators speak espanol only. If it goes OK, you will get a ´secret code´ and have to find a RENFE machine (hence in Espana) and retrieve the booked ticket with that code.

For other REServations -in other countries, its just pot luck if you hit an operator who maybe habla espanol.