Connecting between Ardupilot on pixhawk and ROS/MAVROS on companion computer

I have a question regarding establishing a connection between Ardupilot on pixhawk and ROS/MAVROS on companion computer (Home - MAVROS Tutorial). I have a jetson nano connected to a pixhawk(in Telem2 port on pixhawk) and also a lidar connected to the same pixhawk(I2C) and want to view the rangefinder(lidar) data on the jetson nano in /mavros/distancesensor/rangefinder/pub . How would I type the roslaunch line(e.g. roslaunch mavros apm.launch fcu_url:=udp://:14550@) to connect ardupilot and ROS for my case? Hope you guys can help…

http://wiki.ros.org/mavros#Usage