Can’t upload images in post, newbie help.

Helo eveyone, I’ve just started my blog and came to posting an image in a post and I recieved this message: “Unable to create directory /home/wiimdav1/public_html/wordpress/wp-content/uploads/2007/03. Is its parent directory writable by the server?”

I’m completely new to all of this, someone from http://www.install4free.wordpress.com installed wordpress for me.
I also have Filezilla if that helps.
Thank you for any help, Andy.