update to 3.5.2

i am trying to do the automatic update to my wordpress and i get the following screen after i put in my password, etc.:

Downloading update from http://wordpress.org/wordpress-3.5.2-partial-0.zip…

Unpacking the update…

Warning: copy(D:/Inetpub/civicpolicy/wp-admin/includes/update-core.php) [function.copy]: failed to open stream: Permission denied in D:\Inetpub\civicpolicy\wp-admin\includes\class-wp-filesystem-direct.php on line 200

Could not copy files.

Installation Failed

what do i need to do to fix this?
thanks!