It's just like here on YT, you browse the PINS (threads) and see what interests you and then you can comment on them, and/or like them so it reflects your style on your profile, and/or you can pin them to add to your boards for your own future reference and so you can share cool things/ideas with your followers.
But, just like YT, it works best when everyone contributes by starting your own PIN (thread) by uploading something interesting that you come across. The more that is shared, the more there is to browse
