Unable to run launch file

I am trying to execute launch file for Ex 2.2 but getting this error.

Hi @gat.vab,

Did you create the package?

Have you compiled and sourced it?

cd ~/catkin_ws
source devel/setup.bash
rospack profile

PS: This course assumes you have a knowledge of ROS Basics.

No I did not compile and sourced as that step was not mentioned in the instructions. Thanks for that…will work on ROS basics first.