All you need to do is log in or register an account at http://www.google.com/friendconnect. Then, add your site and click Gadgets. Next, click the "Comments" as illustrated below to get your HTML code as usual.
After adding the Comments box to your site, click "Moderate" then click "Comment moderation" as illustrated below. Change the moderation style to "Approve prior to display" to moderate your comments every time before it is visible to other visitors.
I hope this tips will help all the webmaster to avoid spam comments and save money in the same time.
Written by: Xaivier Chia