You will find published and unpublished reports under "Reports" and then "All reports" in the left menu. Go to "Unpublished" reports. Then click on the report you want to publish.
Once inside the selected report, press the "Invite and publish" button.
Choose which board members the report should be sent to and press "Publish".
You can also invite users to edit the report. Choose which board members will edit the report and press "Invite to edit".
When you have clicked "Publish" and approved the publication by pressing "OK", the report will appear under "Published".