We probably need to understand a bit more about how your system is set up.
I am assuming you are running a MQTT broken in the Bluemix cloud. Again, assuming you are familiar with all the set up necessary to be able to subscribe or publish msg on specific channels, you are trying to configure a MQTT node in NodeRed, on the server end, which for you to consume the received sensor data captured using Dragonboard 410c, is this correct?
To receive the data from the cloud through MQTT it is the same - configure your MQTT client a subscriber to the channel where you know your MQTT publisher on the server end will be spitting out data.
You can refer to NodeRed in terms of the configuration of the (MQTT) node. http://nodered.org/docs/creating-nodes/config-nodes