Like you may already know, your sub domain is a subset of your already existing domain. Take for instance, news.techtimes.com.ng is a sub domain of techtimes.com.ng.
I want to show you how you can easily link your sub domain to your blogger blog. Now let's get started.
==> Go to your Blogger blog’s dashboard
==> Navigate to Settings > Go to Publishing
==> Click the “Add a custom domain” Button
==> In the box below “Advanced Settings”, enter the subdomain eg news.techtimes.com.ng (please do not www)
==> Now hit “Save“
As ususal you will get An error message that will be displayed. Don’t worry. Just leave the page open.
==> Create a new browser tab or window
==> Login to your Domain name provider's dashboard and navigate to your CPanel and click “Advanced DNS Zone Editor”
==> In the drop-down, choose the domain name of your site
All you need to do now is create two CNames using the details displayed in the error message on your Blogger dashboard by filling the fields under the “Add a Record“.
==> Enter “news” in the “Name” field (without the quotation oh!). You can use any name though.
==> Enter “1800” or “14400” as “TTL”
==> Select “CNAME” from the “TYPE” drop-down box
==> Enter “ghs.google.com” in the “CNAME” field
==> Click the “Add Record” button.
Next, repeat the steps above for the second CNAME displayed in the error message on your blogger dashboard.
Once you’ve successfully created the two CNAME records, return to your Blogger dashboard and click the “Save” button.
It should save successfully now, try visiting your former blogspot url, it should automatically redirect you to news.yoursite.com.
Hope this wasn't too difficult? If you have any question please fell free to ask.