How to edit comments Form in Twenty thirteen Theme

I have a question regarding the Leave a Reply section at the bottom of the Twenty Thirteen WordPress theme. At the bottom of a page, you will see the area that asks for your Name, Email, Website, and then an option to write in a Comment.

I wish to change/replace the word Website with Country with an esteric sign as mentioned with Name and Email and that should work accordingly but i am failed to do so. pls help me to add Country button instead of Website.

Thanks and best regards.