In order to use the valve, the threaded parts and body need to be cleaned. If compressed air is present, use it for cleaning. Make sure there are no impurities.
With an appropriate wrench, screw the valve at the threaded pipe. Use hempen tape or similar product compatible with PTFE fluid, as it is needs to be employeed in order to get a correct sealing on the threadings. Only use in adequate quantities, since an excessive employ could damage the couplings.