libdialog is a library that helps developers when writing code that creates a interface for interaction with the user.
See the file "test_libdialog" then you see how "libdialog.shl" works.
You need two files to execute your script or one if you put a line recursively, but it's not recommended. In the first file you have to put your script; and in the second file you should only to put the executable of "libdialog.shl" with name of your script as parameter.