If the file or installation media is not visible, use the browse button at the end of the field box to browse and select the ISO file/media.
Click the Add button to add new media/file if there are new media/file. If you want to use the existing file/media (should visible under any of the Hard Disks/CD/DVD images/Floppy images), please select one.
Find, select the media/file and click Open.
The media/file should be visible with full path of the location (at t he bottom). Select the desired media/file. Click the Select button.
The available media/file should also visible in the drop down box. Select the desired file and click Next.
Click Finish button to start ReactOS installation.