Fore-going pages have expressed very briefly the writer's approach to Zettelkasten with the use of PmWiki and a few other tools. There is quite a wealth of similar approaches on Zettelkasten and those simply on note-taking -- whatever is one's choice, it is a valuable endeavour to develop good note-taking, a skill that will keeping returning good value throughout a life-time.
Given the effort and time spent on these notes, it goes without any argument that regular backups are critical. As the choice outlined in this presentation is the 'Standalone' version, one simply needs to back-up the 'pmwiki' folder in the C: directory -- preferably on a portable hard-drive as well as in cloud-based storage.
Do as well, the backup of the 'fmroot' folder together with your 'myscript.ahk', if one has chosen to use these with your PmWiki setup.