Coraline won't allow upload of image from my computer

Hi all,

It would seem like this question must have been asked before, but I can’t find it…

Coraline SAYS that it’s easy to replace the header with a custom one: “You can upload a custom header image to be shown at the top of your site instead of the default one”, but every time I try to actually upload my 990×180 image (I’ve tried both jpg and png), all I ever get is:

“Unable to create directory /home/catdan/ourblog.greenhillslawnandgarden.com/wp-content/uploads/2012/02. Is its parent directory writable by the server?”

Does anyone have any ideas as to what the problem might be here??

ETA: The site also won’t allow me to upload new media at all!! And I get the same error message every time. Something is NOT right at all here…