The only rail company in Spain is RENFE.
They have a web page here.http://www.renfe.es/
Spain has a modern rail network.
There is a high speed rail network between Barcelona and Sevilla via Madrid.
There is list of Spanish train vocabulary on this page which may come in usefulhttp://www.lingolex.com/trains.htm
A strange this when choosing trains in Spain is that the names of trains can be confusing.
The rapido and expreso trains and actually quite slow so look at the journey times before bying a ticket.
I made this mistake a few years ago and spent 2 hours stopping at every station and went a very short distance from Barcelona.