First off, you need to post a link to your website, a bogus url does us no good whatsoever and there's no way to help someone if we can't see the problem ;-)

The way nuke is setup on your ftp is as follows:

html/themes/yourtheme

By the sounds of your post, you installed the theme in the html folder which is wrong. If you look in the html folder, you will see a folder called themes, that is where all the themes go.