The best way to start even if you don't choose to follow on with it, is a structure learning program. When learning to develop its frankly more important that you do not learn bad habits so taking a run through at least the early steps of a structured course is a good idea.
This course is free, doesn't take long at all and will take you from "installing Unity" to creating some of the most common scripts you will need in Unity.
This course goes on into more advanced subjects if you would like to carry your knowledge forward. Other articles in our guides section here will take you into more specific topics.