Logo Modification

My client has a flash logo (I know, I know… but I can’t talk him out of it) and he want to use it as his site logo.

I found the HTML code section that I need to insert in order to add the flash file (via WP Beginner… http://www.wpbeginner.com/wp-tutorials/how-to-embed-swf-in-wordpress-posts/). But unfortunately, I need to add it in the logo section, not in a simple post or page.

I was hoping you could point me in the right direction as to what file I need to edit to add this code.
Thanks in advance,
Cara