Someone just shared top 11 point`s on my f/book timeline by beating someone else`s point score for which it shows me top with 6,354pts and i have a couple question`s

1 - why do never see my score on my timeline unless someone share`s it ?

2- how do i have so many point`s is it from when i first started playing or does it start at the beginning of every season ?

3 - how do top 11 point`s system work