so i have this c++ code https://github.com/erlerobot/ros_erle_takeoff_land/blob/master/src/main.cpp#L21-L24

and I want to run+test it on Gazebo simulator, any idea how can I do this I have ROS indigo installed in my laptop and Gazebo 4 all under ubuntu 14.04. I'm a beginner so if can provide me with the steps that will be great :)

Thank you