Windows 10 How to backup Outlook Calendar data and restore

Using a search engine I have tried to find how to backup and restore Outlook Calendar data, but failed so far. I see "export" but it is not apparent to me yet. I have done a search on the letters "pst" on my hard drives, but did not get a hit on a file with that suffix. It must be simple, but not for me. Using a different program -- Calendar Creator -- years ago, I lost all of my data, and started using Outlook. Tediously typing in from hard copies of the Calendar Creator files to Outlook Calendar worked. I do not wish to something like that again.