When you first join Blogger, it gives you the option of using your Google+ account to identify yourself in Blogger, instead of a separate Blogger ID. However, if you use Google+ to access Blogger, it would show your full name in posts, and not an alias. If you want an alias, you will need to unlink your Google+ sign-on from Blogger, and use a separate Blogger ID, as Google+ doesn’t give you an alias option. Here’s how to do it:
1. Go to your Blogger Dashboard Homepage (http://www.blogger.com).
2. On the left hand side, click the little wheel at the top of the screen (Blogger Options).
3. Click “Revert to Blogger Profile.”
4. On the following screen, click “Switch to a limited Blogger profile.”
5. Confirm your profile and set your new username. This will be the
display name for your blog posts and comments across Blogger.
6. That’s it!
Incidentally, if you want to use Google+ (instead of a Blogger ID) to identify yourself, follow steps 1 and 2, and select “Connect to Google+”, and follow the prompts).