How to make custom urls in blogspot?

How to make custom urls in blogspot?

1.Sign in to Blogger.
2.Select the blog to update.
3.In the left menu, click Settings > Basic > Publishing.
4.Under your current domain, click Set up a 3rd party URL for your blog.
5.Enter your URL, including the www.
6.Click Save.
7.An error will appear with two CNAMEs.