I created a python and c++ node . But I cant see my nodes with rosrun command.

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I am pretty new Ubuntu and ROS . I created a python and c++ node as you can see first and second part . But I dont see my nodes with rosrun command. I have got this nodes on my my_robot packages (kaymak@kaymak-X550JX:~/catkin_ws/src/my_robot/scripts$ and kaymak@kaymak-X550JX:~/catkin_ws/src/my_robot/src$) .Please help me how can I fix the problem?

---C++ Nodes ----

kaymak@kaymak-X550JX:~/catkin_ws/devel/lib/my_robot$ ls
node_cpp

---Python Nodes---

kaymak@kaymak-X550JX:~/catkin_ws/src/my_robot/scripts$ chmod +x my_first_node.py 
kaymak@kaymak-X550JX:~/catkin_ws/src/my_robot/scripts$ ls
my_first_node.py

---Error Messages---

kaymak@kaymak-X550JX:~$ rosrun my_robot 
Usage: rosrun [--prefix cmd] [--debug] PACKAGE EXECUTABLE [ARGS]
  rosrun will locate PACKAGE and try to find
  an executable named EXECUTABLE in the PACKAGE tree.
  If it finds it, it will run it with ARGS.