Creating a page: what you need to begin
A name and a main photo. Everything else — dates, a nickname, the story, the people — can be added any time.
Say whether the page is about a person or a pet. Then a name and a main photo are enough; the dates of their birth and passing sit beside them, and both can wait. You can add a nickname, a hometown and a short story now or later.
The main photo
Under the photo, one choice: Fill or Whole. Fill makes the photo the page's band, cropped around the point you pick, with the name over it. Whole shows every pixel — nothing cropped, the name under it — for a landscape or a group shot. A wide photo starts as Whole, a portrait as Fill; switch any time under Settings → Details.
After the page exists
Start with one memory — a story, a photo, a moment. Then invite the people who were there; the page grows from what they add. For the page's first month, whoever manages it sees a Getting started card under the page's buttons with those first steps in one place — a photo of them, the first memory, and one more person on the page — and each is ticked off once it's done. Not now puts the card away on that browser or phone.
Life events, occasions and the people in their life are kept under Settings, so there is one true answer for each fact. See Memory or record?.
Who can see it at first
A new page starts with Anyone with the link can read it switched on: anyone you send its link to — in a message, in the family group chat — can read it (read, not add), and only the people you invite can add to it. To keep it to them, turn that switch off under Settings → Privacy — then nobody else can open it, whatever they type. Nothing is public until you choose that. See Who can read the page.