Answer by Noumaan Yaqoob:
Start with basic HTML and CSS. Write plain HTML/CSS documents using a plain text editor such as notepad. This will strengthen your understanding of HTML, CSS, web design, layout and formatting, etc.
Blogger uses template tags so you need to learn how those blogger tags are used in an HTML+CSS template. Download free sample templates from the web and study the code. It might look complex at first but if you look at it with concentration you will realize that it is not that complex and quite easy to do.
For WordPress you should learn basic PHP programming. Like variables, arrays, if, else, while, loops. When learning PHP use the official PHP manual it is really good PHP Manual – Manual
To set up a PHP MySQL and Apache development environment on your computer you can try WAMP or XAMPP. How to Install WordPress on your Windows Computer Using WAMP Or use MAMP if you are on a Mac, How to Install WordPress Locally on Mac using MAMP
WordPress has some coding practices which are used by most WordPress themes and plugins. You will get familiar with those by studying other people's code. The default WordPress Themes such as Twenty Twelve are a great starter point to understand template hierarchy. Each WordPress templae uses template tags and functions inside it. Which are actually functions pre-defined in WordPress core files. When building themes in WordPress you don't edit the core files. Instead you use these functions through out your theme. A good starting point for learning theme development is WordPress Codex:
Site Design and Layout