Upon logging in. Go to Settings > Basic > Click Import.
Browse for the backup file ( usuallly an xml file ). Input the captcha word that you see. Once done, click Import Blog.
After Importation. Go Edit Posts > Select Imported. Select the posts which you want to include as posted. Done :D
Importation can help bloggers to transfer their blog post to another one. So, you don't re-type all the blog posts. Or if you having too many sites and you want to handle only weblog you can do this too. Create a back up of all your site then import it to your desired blog site. Take note of the compatibility too. For example, my other site has a back up xml file but it came from a wordpress application, good thing, there are plenty on the web that can change it so it can be applicable to blogger.