Because privacy is important to Google, the search engine needs to know you own a site before it show you certain information about it or enable you to use it's tools. Verification doesn't affect PageRank or affect your site's performance in Google's search results though it is a very important step to take after creating a blog.
Blogs hosted on Blogger (that haven't yet been verified) will have to use the meta tag verification method to verify their blogs. Below are the steps required to verify a Blogger/Blogspot blog in Google Webmaster Tools.
In Webmaster Tools ==> https://www.google.com/webmasters/
1. Click the "Add a site" button on the Webmaster Tools Home page
2. Enter your blog's URL (for example, ogbongeblog.blogspot .com) and click the "Continue" button to go to the Manage verification page
3. Select the "Meta tag" verification method and copy the meta tag provided
4. Go to your blog and sign in
5. From the new Blogger dashboard click the "Template" link for the blog you're verifying
6. Click the "Edit HTML" which will allow you to edit the HTML of your blog's template
7. Click "Proceed"
8. Paste the meta tag (copied in step 3) immediately after the <head> element within the template HTML and click the "SAVE TEMPLATE" button
In Webmaster Tools
9. On the Manage Verification page, confirm that "Meta tag" is selected as the verification method and click the "Verify" button.
Webmaster Tools will check to see that the specified tag is present. If it is, you will be considered as the blog owner and you're ready to start using Webmaster Tools!
Thereafter, you can go ahead to submit your blog sitemap to Google Webmaster Tools and also to Bing Webmaster Tools.
In my future posts, I will share with you reasons why you must verify your blog using Google Webmaster tools and how you can use the different webmaster tools. Just make sure you are subscribed to this blog for you not to miss the tutorials.
Source: Google Webmaster Central Blog