newbie cannot customize css for new header image

the address is http://www.StlDogRescue.com and I’m trying to edit the K2 theme which looks great and easy to modify. I’m trying to create my own css to change the size of the header and insert my own image but my own ‘schemes’ don’t seem to make any changes at all. my image is located at themes/k2/styles/sample/images and i’m working with the sample css.

the way i understand it, with K2 you should be able to add your own css as a ‘scheme’ and whatever your css does not address the default style.css will take care of.

i’ve been working on this a few days and i’ve been able to change the size of the header using css (sporadically) but cannot use css to insert a different image.

here’s the css i changed in the sample css of K2 (i only changed the header)—-

[CSS moderated as per the Forum Rules. Please just post a link to your site.]

FYI – i’m using dreamweaver cs4 to edit the css, then uploading it. i know the updates are working because i can see the changes in the WordPress ‘editor’ (haven’t been able to get xampp to work on my Win7 x64 system).

any help would be greatly appreciated,
thanks,
jtn