Changing the logo dimensions in Course Press

Hi there! I'm setting up Course press to sell yoga trainings. I love it so far but ran into an issue. I want to display my logo instead of the course press logo. When I upload it via the theme editor, it shrinks it down too much and makes it almost unreadable. Where can I change this in the theme files so it will pull the logo I want keeping the dimensions?

Here's the link where you see the image as a shrinky dink. http://yogatraining.4theloveofyoga.com/

Thanks!
Sonya
ps I also attached the logo image