Replace "/Volumes/Untitled" with the name of your USB drive or external hard drive.
macOS High Sierra 10.13.1: Features and DMG Installation Guide macos high sierra 10.13.1 dmg
If you simply need to , search for the official Install macOS High Sierra.app (version 10.13.1), then use createinstallmedia in Terminal — not a .dmg . Replace "/Volumes/Untitled" with the name of your USB
To install macOS High Sierra 10.13.1 from the DMG file: macos high sierra 10.13.1 dmg