labels for basic comment form on front page

I’ve been looking but I don’t see it?
I want to change the labels on the basic comment form that shows up on the first page of the 2013 theme.
I’ve looked through (I think) all the php templates – nothing!
And a general question, when you look at the source page of a site, you see everything, but when you look at the php files in the admnin section or the actual files that are on your server, all you get is just some generic stuff (not very useful). With the exception of the header.php file the rest of them….??!! there’s almost not enough there to work with, this might be great for automated blogs, but for static pages ??!!!