Thanks Jason. This seems to be working now.
The client has now asked me to add the file upload feature to the form. I select the form and click 'edit contents' and add it to the form. I think I have done this correctly. When I edit the element to make it not a 'required field', it does not allow me to do this when I uncheck the 'required field' option.
Also, Webassist instructions say, if your form contains a file field, the 'Form Upload Settings' option will be available on the 'Form Function' tab. I am unable to find the 'Form Function' tab. Is this all I need to do to make my file upload feature and the rest of the completed form fully function?