Resizing Logo

Hi, First off, I am extremely new to wordpress. So please bear with me. I followed this person’s advice trying to insert my logo. http://wordpress.org/support/topic/theme-zenon-lite-image-to-replace-title?replies=7 It worked, But now I have a massive logo on my homepage. My question is, how do I resize the image to it’s original size? I’m not sure why it showed up so big. The site is thisblog.us Any help is greatly appreciated.

http://wordpress.org/themes/zenon-lite/