Login to your namcheap account.
Step 2::
Scroll down and in the bottom-left space you'll see a box to enter your domain name.
Enter the domain name to be used for Blogger blog and click modify.
Step 3::
In the left sidebar click on the subcategory all host records in the host management category.
step 4::
Below IP ADDRESS/ URL enter the following.
Put ghs.google.com across www.
Enter http://www.yourdomainname.com across @.
Below Record type select URL Redirect(301) (for SEO) present across @ and select CNAME(Alias) present across www.
6. Go to your Blogger account.Now follow this ::
Under Setting --->> Publishing --->> Custom Domain, choose 'Advance Setting' and fill in your new domain name correctly.
Save it.
Now,tick redirect yourdomainname.com to www.yourdomainname.com.
Remember to save it.
That's it.We are done.