Click an empty part of the upper display (image below) until a menu appears. We will now configure the top menu options to reflect the ones of most use. To edit there is a tools palette with various tools (image below). To play the song you will need to hit the space bar with the Control key held down otherwise the song position pointer will return to zero. The former is a much more conventional way to work.
This puts the session into song mode as opposed to pattern mode. Go to the transport and click the small led display dot next to song (image below). Go to FILE / New from template / Basic to open a new session. Open FL Studio and configure it accordingly.