How to Set up a custom domain for a Blogger?

Set up a custom domain

When you buy a domain, you can personalize your blog’s website address.

Step 1: Buy a domain

See if you can buy a Google Domain or buy a domain from a non-Google provider. To buy a Google domain:

1. Sign in to Blogger.
2. Select the blog to update.
3. On the left, click Settings  Basic.
4. Under "Publishing," next to "Blog Address," click Buy a domain.
5. At the top, search for a domain.
6. Next to the domain you want, click Buy.
7. To finish buying your domain, follow the on-screen steps.

Note: If you’re an administrator, learn more about managing domains registered through Blogger.

Step 2: Set up your domain with your blog

2. 

Connect to your non-Google domain from Blogger

3. 

Step 3 (optional): Add www. to your domain

To change your domain (example: mydomain.com) to www.mydomain.com, set up a naked redirect.​

1. Go to your domain provider’s website.
2. Open your DNS settings.
3. Enter your domain name in the format example.com.
4. Add four A-records which point to Google IPs.
   • 216.239.32.21
   • 216.239.34.21
   • 216.239.36.21
   • 216.239.38.21
5. Sign in to Blogger.
6. Select the blog you want to update.
7. On the left, click Settings  Basic.
8. Under "Publishing," under "Blog Address," check Redirect [mydomain.com to www.mydomain.com].

source: https://support.google.com/blogger/answer/1233387