How to change sidebar text/content

HI.
I’m using this theme http://www.blogohblog.com/wordpress-theme-nublu on my blog and i want to know how i rewrite the sidebar content to my language. It’s written Arquive, tags, files, etc. I want to rewrite these titles.
So, which file i need to edit so i can make these changes?

Thanks! I bet this is a stupid question, but i’m still noob to this whole thing =)