Move inside the ROS workspace and Create a ros package that depends on TF, roscpp, rospy, turtlesim.
Assuming workspace name is 'robotics'
cd robotics/src
catkin_create_pkg lab_1_tf tf roscpp rospy turtlesim
Move to workspace root and build the package
cd ..
catkin build
or
catkin_make
move inside the package and create a folder called scripts
cd robotics/src/lab_1_tf
mkdir scripts
This folder will hold all the python scripts required by the nodes.