Error: package 'beginner_tutorials' not found [closed]

edit

When running the following command,

rosrun beginner_tutorials add_two_ints_server.py

This error pops up:

Error: package 'beginner_tutorials' not found

I have followed each step from the tutorial (from tutorials 1.1 to 1.16), try a lot of ROS forums answers and nether solutions worked. What is really weird is that I can use roscd begginer_tutorials and in rospack list "begginer_tutorials appear", but when I try to use rospack find begginer_tutorials the same error pops up.