Indeed, the return of the 'how to' blog posts! I'm writing this post as per the request of a friend using blogger. Thought it might come in useful for others too. Note that I'll be going real slow on details so nobody gets lost along the way. So, let's jump right on topic!
Step 1: Go to your blog home page: https://www.blogger.com/home
Step 2: Click on your blog name in the blog list(if you have more than one)
Step 3: You are now on your blog dashboard. You'll find the menu on the left with "Overview, posts, pages, etc.." options. Go to "Template" in the list.
Step 4: Here, you should find two buttons. One of them is "Edit HTML". That's your guy. Click him!
Now, it is strongly advised to keep a backup copy of all the codes which will be displayed in the window that pops up. Just copy-paste those codes in a text file somewhere and save it.
So, that's it. If you have any other queries in those regards, let me know.