how to get facebook user avatar via api?

Question

Facebook

Hello.
People can tell you how to do this thing:
There is a button on the site, by clicking on it we send a request to the user to place a message on his wall with a link and a description, how he confirms the request, the record is posted and his avatar (or link) is pulled out and this avatar is added to the slider, but this is nonsense, the main thing for me is to get the address of the avatar)
How can this be implemented, I look at the documentation for the second hour, nothing is clear at all, I did the same thing on VKontakte in 5 minutes

Answer 1

all hang up, figured out, did everything