Question: how open djvu file in window?
Answer: Click the “Open” button to browse for the DjVu file to be opened on your PC in Windows Explorer. ... 
Your DjVu file is opened in DjVuLibre DjView.
To open a DjVu file in WinDjView, drag and drop the file into the window of the program or click the “Open” button to browse for a file using Windows Explorer.