basically you can set a variable like
ebit_pad = "/the/path/to/my/samples/"
You can do that at the top of the buffer or in your
init.rb, which resides in the directory
.sonic-pi (under Linux this is in your home directory, not sure where to look for it under Windows). This file will get loaded anytime you start SP and the contained variables will get initialized.
Furthermore have a look at the chapter 3.6 and 3.7 to see how you can reference samples on your harddisk (keywords: indexing and filtering samples).
So Sam calls a directory via
ebit_pad and filters the contained sample filenames via two strings “120” and “Cm”.
Hope that helps.