Below is the guidelines on how to point your domain for example yourdomain.com to Blogspot and replace your Blogspot URL such as yourblog.blogspot.com:-
1. Firstly you need to point the A records (in DNS) for your domain as below. You may request your hosting provider to add it for you as normally it only can be done from their end.
216.239.32.21
216.239.34.21
216.239.36.21
216.239.38.21
2. Then you need to update your Blogger settings. Below is the guidelines from Google:-
http://www.google.com/support/blogger/bin/answer.py?hl=en&answer=55373
Wait some time for the DNS to propagated and your are done.
