my apple watch say no connection for cellur use

Please explain what you see to make you think it is not working.

In your iPhone's Watch app go to My Watch > Mobile (or Cellular) Service and tap to select. The top entry just below the title bar should show the name of your cellular provider.

On your Apple Watch, press the Side Button to open Control Center and look for the cellular button (usually the top left button on the screen).

See pictures in

Set up cellular on Apple Watch - Apple Support

If it is dark then cellular is not available or enabled (call the cellular provider)

If the cellular button has a white background then cellular is enabled an available, but not in use because the watch prefers to route through your iPhone.

If the cellular button has a green background your watch is using the cellular service

Hit Send too soon. Adding:

Tap the Cellular button and check the settings in the page which will open.