So for the latest version, I wrote a new help file from scratch. The complete rewrite describes all modern program features with enough detail for the average user (not necessarily a geek) — without getting too mundane hopefully. Press <F1> key to check it out. It is an amagalmation of program information, tips and tricks, demo videos and the most popular blog posts over the years. Hopefully it will be the only stop you need for getting help on xplorer². It is double the size of the old help manual!
I recommend you read the overview section at least, and for other details you can search for menu command names you are interested. When you are using a dialog box, pressing <F1> will open the manual at the correct spot explaining the current dialog; there are details about all the controls you see.
If you prefer a printed version, you can use the Print command of your browser to create a PDF out of it. A volunteer is working to create a CHM version as we speak — more on that later.
The new manual was a big job, therefore v5.5 is rather short on new features, but there are bugfixes and small improvements as: (see the changelog for the full list of changes)
Please use Help > Check for updates menu command or the equivalent from ribbon's FILE leftmost tab to get the new version. If you don't have xplorer² installed try the download page for your free trial.