Just a simple modification on the post-header

I use the Hickory theme and this theme has uses this order:
1- “post-image”
2- “post-header”
3-“post-entry”

What I need to do is change the post-header, for the first position. In HTML is just changing the positions (I used firebug), but when I change the position of the corespondent parts in the php file, nothing happens.

Now two problems can exist here, since when I change a div or class id, nothing happens to.
1-I’m doing things wrong for changing the position of the post-header;
2-I’ve some problem with the connection between my server side and my blog, that I don’t know.

Thank you very much in advance.

P.S. I’m using a child of the parent theme and I copy only the php file that I wanted to modify to the child file.