You almost always start out coding with RxJS by creating a stream of static values. Why static values? Well, there is no need to make it unnecessarily complex, and all you really need to start reasoning is an Observable. As you gradually progress in your problem solving, you might replace the static values with a more appropriate call to an AJAX call, or from another asynchronous source that your values originate from.
You then start thinking about what you want to achieve. This leads you to consider which operators you might need and in which order you need to apply them. You might also think about how to divide your problem up; this usually means creating more than one stream, where each stream solves a specific problem that connects to the larger problem you are trying to solve.
Let's start with stream creation and see how we can take our first steps working...