Translating Theme

Hi! I need to know how to translate some options in the blog section like “leave comment”, “posted in” or “tagged” and the navigation options like “older posts” or “newer posts” as well.

I´m trying to translate it to spanish and i assume that i must edit some templates using the theme editor, am i right? any other way to do it?

Here’s a link to my blog –> http://luismiguelsanmartin.com/blog/

Thanks in advance 😀