To the right of the timeline there are buttons to add a step and another to pull up the Steps Details panel. Upon opening it, you'll see little move icons in the top left corner of each step, and that will allow you to reposition them.
You can also set camera from here as well as delete steps.
Another setting available in the Steps Details panel are Show step overlays. This creates a rectangle text box at the top of the screen that you can type into, and essentially write your narrative here. So if somebody is going to access the Flow with a link and you want them to have some kind of context or background, this is a good place to put that. The settings allow you to have text overlays show while in the editor, but also while in meetings.