Step 1: Login to your blogger account. Go to settings, publishing.

Step 2: Click on custom domain, Select switch to advanced settings.

Step 3: Enter your domain name at the your domain field. Use URL format without the www. Select no from use a missing file host question. enter the word verification and select on save settings.

Step 4: After saving, change URL format and add the www. in your URL and save settings again.

Step 5: Modify DNS settings in your server, see for more information on how to edit your DNS.