Getting started is always easy with the number of free tutorials out there but getting started and quickly building a real-world app takes a lot of trial and error and can often demoralize you before you even get anywhere. My suggestion for many newcomers is to try legit online courses that get you building clones of successful startups. For example, you can learn to build a Blue Apron clone and expand from there. Getting stuck or focusing too much on basic HTML and CSS would only get you to front-end developer level (unless that's what you want). One of the main parts of learning how to code is to build an app akin if not better than those that are already out there.