How to implement access to email, wall posting through vk api?

Question

API

As I did not connect api, but everything does not come out to get access. I already found what I need to do callback to blank.html
But then the site afisha.ru comes to me and I see that it is somehow configured and allows you to make a request to email, wall.post.
How and what to do in order to get something like this?
the link through the site asks for rights
Thank you!