Steve McKenzie's Drupal Sandbox code which fathered the Drupal Salesforce module and comprised its initial import, was composed of an install and module file, as well as a sub-directory of includes.
I went ahead and made a fresh 4.7 drupal installation and installed the module (only dependency: the core profile module should be enabled, since salesforce adds some profile fields) as is.
I went to administer » settings » salesforce, and filled in the username and password of my developer CRM account. I left the other options as per default values.
Now when I edited an existing user account I expected a web-to-lead to be created.
However I got an error because the necessary Profile fields had not been created by install (code now rectified).
So, reinstalled with install script corrected, and upon editing Personal Information for fred, a lead was created in salesforce for this user.
[to be continued (exciting, isn't it?)]