It will take 1 weeks or 7 days to complete the course, and about next 7 days of practice to get comfortable with HTML. The key is to apply your learning and build projects. This course will give you all the basics knowledge that is required to build the website. With more practice, you can start building websites, emailer for clients as well and start charging for your services.
There are no minimum system requirements for coding HTML program, you can do it in any text editing program like notepad with any operating system. For testing your work, you will need an HTML5-compliant Web browser application. The latest versions of Google Chrome and Firefox (both freely available online) will work fine for this, as will Internet Explorer 9 or higher.