As you can see, the GUI is very simple. Add .lit files via "Select .lit file(s)" button or from file menu. You can also drag and drop files to the listbox, send them from Windows Explorer or from Search window - we'll get to that later. Selected files are shown in the listbox, you can remove them via right-click menu. Note that you can select several files at once and also select several times. If you check "Create 'filename' subfolders for extracted files", then a "filename" subfolder will be created and used for files. Ie, if you extract files from "Alexandre Dumas - The Count of Monte Cristo.lit" and have output folder as "c:\My Literature", then folder "c:\My Literature\Alexandre Dumas - The Count of Monte Cristo\" will be created and all extracted files will be moved to there. It is really recommended to enable that option when extracting from multiple files.
Rest of that tab should be self-explanatory - also there are hints for most items, just hover your mouse cursor over the controls.
After you've made your choices, click on "Extract" or other action buttons. GUI will start working on those files. As you can see, files are extracted to the temporary folder and then moved to your selected directory. ConvertLIT GUI is a graphical user interface for the wonderful command-line tool ConvertLIT. With ConvertLIT, you can extract files from Microsoft proprietary ebook format .lit (see http://www.microsoft.com/reader/ for more information), you can also downconvert (ie remove DRM protection) and inscribe lit files.