GeekMan's post in Filling in form field from url variable was marked as the answer
I got it to work!!!
I was putting the variable in the wrong place. At first I did this: form-builder/test/?course_name=Intro%20to%20Computers
The form-builder should really just be: form-builder/test
and the link calling it should be: /registrations/test/?course_name=Intro%20to%20Computers
this calls the form and puts the variable into the course_name field like it is suppose too.