The latest Salix releases are freely and easily available as ISO image files from the Salix download page, via direct download link or torrent file.
An ISO image is an archive file of an optical disc. It can be easily burned to an optical disc by using media authoring or disc burning software. The resulting disc should contain the contents of the .iso file, but not the .iso file itself; if it does, you have made a mistake in the process. These days, it might be more usual to write the .iso file to a USB stick, using a tool like dd, or any image writing software.