Hey @sliawatimena, according to your pic you are being able to receive data from the mDot.
However, it seems you are sending a "Hello World" text, which our sample Node doesn't recognize. As explained here, our node understands data in this format:
The Node will automatically create a data source with tag=DEV-EUI and variable with name "Tombol" and value "1".
If you want to build your own node using MQTT, you can easily do it by using our MQTT broker and nodered's MQTT client.