To install, extract the files to a new folder on your harddrive, for example: c:\nwc2ly. Open NoteWorthy Composer 2 and start a new project or load an existing file (otherwise the User Tools option will be disabled). Press Alt+F8 to open the User Tools dialog and click the New... button. Enter "NoteWorthy Composer to Lilypond exporter" as name (or anything you like) and as command: "c:\nwc2ly\nwc2ly.exe" (or whereever you placed it).