you will need to source the environment setup file like you did at the end of the create_a_workspace tutorial:
$ cd ~/catkin_ws
$ source devel/setup.bash
$ roscd beginner_tutorials
you will need to source the environment setup file like you did at the end of the create_a_workspace tutorial:
$ cd ~/catkin_ws
$ source devel/setup.bash
$ roscd beginner_tutorials