You'll now see a Publish button at the top of your screen in Edit mode. When ready, hit this button: the draft version you see when editing will become the published version, seen by Viewers. Straight-forward right?!
Quick note on the versioning, or the importance of naming your versions
A report is rarely a finished product, it keeps being edited as needs from the business changes and/or more data become available.
But what if you made a change, but need to revert it for x y z reason?
Well, the best way of preventing the chaos to develop is to name the different versions you build, so you can come back at any point in time to previous versions.
Once reaching a stable version, under File, Version History, click See Version History. You can now name the different versions. No need to name them all, only the main ones, so when you need to come back to them, just tick the Only show named and published versions, and you'll be able to revert to any of these by hitting the Restore this version button at the top of the screen.