My b2evolution Version: Not Entered

Hi Folks,

I'm a total newb here so please bear with me!

I have just installed Key west and it's running ok exept that I'm getting to following errors when I access the 'file' tab:

File management
The blog's media directory «media/blogs/a/» could not be created, because the parent directory is not writable or does not exist.
The blog's media directory «media/blogs/b/» could not be created, because the parent directory is not writable or does not exist.
The blog's media directory «media/blogs/links/» could not be created, because the parent directory is not writable or does not exist.
You don't have access to any root directory.

I know how to chmod but which files folders do I need to change and what to, 766?

Thanks guys.

Cheers.

Jon.