When search engines crawl your website, they look for the links in your site as well. The text of the link is also very important, because search engines also note this. Since each and every post in your blog has its own link, you must make sure that these links are quite meaningful.
When you publish your post in blogger, the first few words are selected for making up for the link of that post.
For example, if the title of the post is “how to blog using flock in blogger”, then the link would be something like http://blogname.com/......../how-to-blog-using-flock.html
In the example above, if the blog title does not contain the “in blogger” text.
But it would be better if the link were http://blogname.com/......../blog-using-flock-in-blogger.html
So to do that, first publish the post with the suitable title which you want to have as the link. Then after publishing, you can change the title to a more detailed one.
Note by changing the blog posts title, the blog URL does not change.