For an explanation of what Html2Slideshow is, please read the text of the Html2Slideshow-Homepage on http://www.uplawski.de/html2slideshow.html. However, the referenced page is only available in German, at the time of this writing (end of March 2009).
In the document, you are currently reading, I describe, how the graphical Shoes-surface for the Html2Slideshow-program is used. If you want to use Html2Slideshow on the command-line of a Unix-shell or in a DOS-window, instead, the argument -h or --help will print the following usage-information:
Usage: ruby html2slideshow.rb [options]
or html2slideshow [options]
Specific options:
-d, --debug [true|FALSE] Switch on debug-mode. Will generate log-messages during processing
-s, --source SOURCE DIR Read HTML source-files from this directory
-t, --target [TARGET DIR] Write slideshow-files to this sub-directory
(if not provided, SOURCE DIR is used)
Common options:
-h, --help Show this message
--version Show version
You need Shoes. Without Shoes, you will not be able to use HTML2Slideshow over the graphical user interface and have to stick with the command-line. Get the graphics toolkit and all the background-information you may need, from the Shooes-homepage: http://shoooes.net/
The generator and its GUI exist, thus, well separately from each other to allow different uses of the program. While html2slideshow.rb is the main Ruby-script, that can be used on the command-line, html2slideshowDialog.rb contains the definition of the Shoes-dialog, explained below.
I believe, that you know already how to start a Shoes-application, but just for completeness, do it like this:
So far, two options are not accessible to the console-program:
Both features are explained further below.
The user-interface consists of a few different dialogs, but for the most general task of creating slideshow-files from original (X)HTML-sources, the first or main dialog offers all the functionality you need.
When you start the program, this green dialog is what you see, at
first.

The simplicity of the Shoes toolkit results in some small inconveniences, but they are almost entirely restricted to the appearance of the surface. In the screenshot above, you notice a less than optimal alignment of the GUI-elements (and there is more to come...). This does anyway not impair the functionality of the program.
I will now explain each element from top left to bottom right:


slideshowis entered automatically, but can be modified. The field can even be cleared, in case that you want the source-folder to contain the slideshow-files, as well. Otherwise, the sub-folder will be created, if it does not already exist, when you click the
Start-button (see below).

Start

Done, but the same dialog is used on other occasions and I have not yet found out, how the dimension of such a window can be swiftly adapted to its current use. Let us ignore that for now, okay? Thank you. ;-)

Back-button to return to the main-window. Do not try to close the window by use of the x-button in the window-frame. Because I need to avoid several dialogs being open at the same time, the triggering buttons will always stay disabled as long as a dialog is opened. Shoes does not allow me another way to keep track of open dialogs, should you not use the
Backbutton. Otherwise, the program needs to be restarted, to activate all buttons again.
Options

html2slideshow.login the current user's home-folder is used, but you can name a different file, after you activate the option by a click on the checkbox. The file will be created, if it does not exist and additional contents is appended, otherwise. As long as the checkbox is not activated, though, no log will be written. Be careful to choose a file, that is not needed for other purposes and none that would be destroyed, when text is added to its end!
Back-button will bring you back to the main dialog. All options have immediately been applied.
Quit
Quit-button you exit the program. In the current version, the configuration is lost each time, when you close the main dialog and thus leave Html2Slideshow. This means, that before you can generate the next slideshow or replace an existing one, you will have to choose your folders and options once again. This will probably change when the program is updated some time, so that your current settings can be saved and restored in the next session.
Quitin the main dialog, the confirmation dialog from the next screenshot pops up:

Howto
Howto-button in the main dialog. You are asked for the command, which opens the browser. Either type the path to the executable or, if the latter is already in the path for executable files on your system, just the name of the browser:

Acceptwill either open the page in your browser or a failure-message is displayed. In that case, you can return to the previous dialog with the
Back-button and alter the browser-command.

About

For each button, that you see on the surface, a keyboard-shortcut
exists, which can alternatively trigger the same action as the button
does. A list of these shortcuts is not necessary, as each one is the
combination of the Alt
-key with the first letter of the
button-caption. For the Howto-dialog
this means, that Alt+b
closes the
dialog, while Alt+a
should bring up
the web-browser of your choice.
In addition, the shortcut Alt+q
is available in each dialog to quit the application completely. Use
the same shortcut again, when asked to confirm that you want to close
down Html2Slideshow.
I am using my own site at http://www.uplawski.de/Provence as an example. The idea for my first C++-version of Html2Slideshow did also arise during the creation of those pages.
The local
directory with all the inside pages, at first looks like in the
screenshot to the right.
What I want, is a slideshow-file for each of those html-files, should they contain references to photos. Html2Slideshow will create those files and spares me the trouble to copy JavaScript and CSS-code in the process.
In the main dialog of the program, I enter the path to the
source-folder: 
Due to the line-break in the path to the (will-be) slideshow-folder,
a slider appears to the right of my dialog. This may or may not
happen, depending on your display-configuration and the length of the
path-entries, you choose.
Next, I just click the Start
-button and a moment later, all
is done. You can, though, use the options-dialog, as explained
above, to alter the program-behavior,
prior triggering the generator.
To the right,
you see part of the result, as the new sub-folder slideshow
has been added below .../Provence/pages.
Inside that folder, I find the new slideshow-files along with the
CSS- and JavaScript-files, that they will use: 