By default, your flights are completely private and only visible to you. You can choose to share selected flights or all your flights with others (e.g., your mechanic, flight instructor, type club forum).
If you wish to share a flight, the platform provides you with an obscure, hard-to-guess URL that gives access to the chart for the flight. Just copy the URL from the address bar on the chart web page and paste it into an email. To share all your flights, use the URL on the Sharing page. Nobody can access your flights unless you provide them with one of these URLs. If you change your mind later, you can instruct the platform to invalidate the link you shared so that it will no longer work.