you could copy and paste it to a Word Document
and then save/print to pdf -
and then upload to FS Memories.
Under Memories you can Create A Story.
As, 'Dennis, has already proffered ...
Once you have your "Story" (in/from 'FaceBook"); as, an example, a "PDF Document" ...
Upload that "Story" (in whatever "Format" you choose) against the individual/person in "Family Tree" of 'FamilySearch'; as, a "Memory".
Here are some "Knowledge Articles" in 'FamilySearch':
What rules apply to uploading memories to FamilySearch.org?
How do I upload memories to FamilySearch?
How do I tag memories of my ancestors or relatives in Family Tree?
How do I tag people in stories and audio files?
How do I add a story to Memories?
How do I add an image to the story I created?
How do I add or edit the title of a photo, story, document, or audio file?
I hope these help.