Ruby on rails国际化西班牙语

I'm creating a fast application with ruby on rails, and after doing a lot of scaffolding and validation I'm very happy with some of the features that are embeded in RoR... but I live in Mexico and all my users would love the application to be in Spanish of course. So, I noticed theres a lot of functions that write actual text in English for example time_ago_in_words and all the errors produced by the scaffolding and validation. I'm creating a fast application with ruby on ra