Use payplans to give away a free PDF but user has to register on website and choose a plan.

I want to use payplans to let users register on my website for free. I want to offer a free pdf. To download that pdf one has to register in a free plan. However, I have no idea how to start it properly. I have several PDFs that I can give away for free. But where do I place it or how do I place it on the website? I can put the pdf in a folder on the hosting or is there a better way to start? I never really got off to a good start with payplans.