Hey okay, so this is how it works. Unless you have a right-click mouse, you hold down control while clicking on the ad. A little mini menu will pop-up. Select SafariBlock Frame. A window will pop-up with the URL in it. Now, if you just hit okay, it won't work, because each ad has a different URL.
The URL will look like...
http://pagead2.googlesyndication.com/pagead/*
There will be a bunch of stuff after the pagead but you want to delete that and replace it with the asterisk so it looks like the URL above. It should block all google ads on all websites.
Or you can just open up the SafariBlock tab in Safari preferences, click on ADD and copy/paste the URL above into the box. and hit add when you're done.