Under each post on Blogger (Blogspot.com), the author name of the post is display as Posted by 'Author Name'. For example on my posts, it's showing as
1. From the blog Dashboard, go to Template -> Edit HTML-> Proceed
-> put a check mark in front of the the "Expand Widget Templates"
option (details: same as the first 3 steps in this post)
2. On your keyboard press the "Ctrl" and "F" keys at the same time to bring up the search box.
3. In the search-box, type in <data:post.author/> then search. The first <data:post.author/> will be highlighted. Replace it with the author name you want to use.For example, I replace it with my author name BJ.
Once replaced, search for next, replace again, until there's no more <data:post.author/> come up in the search result.
Note: in the Blogger template, there are 4 or more <data:post.author/>, just replace all of them with the author name you want to use.
4. Save the template. You done !
There's are 2 ways to change the author display name for Blogger blog, one is edit the Google profile, as mentioned in Blogger