CSS help for logo to header

Hi there,

I’m struggling to find the CSS code that will allow me to upload a logo and insert that as my header. My website is http://www.stridefit.com and uses the Brand New Day theme – this does not allow header customization.

I’ve tried to search for previous posts that provide this support for the theme, but to no avail. I would hugely appreciate help.

Thanks a million in advance.
Rob

The blog I need help with is stridefit.com.