SimonIoa 77 Master Poster

I have created a facebook app. Often on my wall i see others share links. I see that the posts have an image and below a small text, below that the url of the website. When you press first it redirects you to i.facebook(some url) and then goes on the website. How can i do that? i mean when i post from the page i have created for my website i can only post a link or a photo with some text and so on... Do i have to have an facebook app? I do. how do i post from there? Sounds stupid but i need some help