Once I have created a PDF and what to change it to a PDF Fill-In Form - the program keeps shutting down and never creates it!

What program,Operating System, and computer?

There are many programs by Adobe (Acrobat and LiveCycle) that can create forms and even 3rd party programs like OpenOffice.org write that can create a PDF from a form.

You should be able to open the Forms Tools and manually add form fields.