I want to use an image that isn't 198 by 940 (the default size for Tenty-Ten header images). I've seen a lot of posts recommending that the user change the functions.php file. I have 3 specific questions:
1) I can't find the functions.php file. Where is it?
2) My site is hosted by WordPress itself. I read that WordPress does not allow custom themes on sites it hosts itself. Is that why I can't find functions.php?
3) Is it possible to change the header image size via the CSS stylesheet? How? I tried this code and it didn't work:
margin:7px 9px 0;