Combine File Download Key with Specific Page

The API Functions page at http://www.s2member.com/codex/stable/s2member/api_functions/package-functions/#src_doc_s2member_file_download_key()

states the following regarding the function: s2member_file_download_key()

“When /?s2member_file_download_key = a valid Key generated by this function, it works independently from Member Level Access. That is, a visitor does NOT have to be logged in to receive access; they just need a valid Key. Using this advanced technique, you could extend s2Member’s file protection routines, or even combine them with Specific Post/Page Access, and more. The possibilities are limitless really.”

I want to combine File Download Key with Specific Post/Page Access, so that non-members can only access specific pages for 24 hours.

I know nothing about php, very little about HTML.

How can I combine these to accomplish this? Please make it simple to understand :)

Thanks in advance