unable to upload images…permissions problem?

After an attemtp to upload an image in WP I get the following message:

“Unable to create directory /home/silvey/public_html/wp-content/uploads/2009/10. Is its parent directory writable by the server?”

I’m not too familiar with this but I have tried to change the permissions on the uploads folder and I cannot get this done. I’m getting this message after clicking to set permissions:

“FileOp Failure on: /home/silvey/public_html/wp-content/uploads: Operation not permitted”

Any ideas on what I’m doing wrong? I can change permissions elsewhere.

Thanks for the help. sam