I've already did it. It still doesn't work. But you know, I figured out why. The problem is in my host.
As I'm a neewbie and as I not sure if I could set pixelpost up, I signed up a free host (10gbfreehost.com). They're quite alright but there are some routines that only works if you have a payed account. Probably working with APIs (outbound instructions) is one of those.
I'm experiencing the same problem with Defensio API. Carl, from Defensio, was the one who'd told me about the free hosting problem.
I've asked the host support for a solution.
I'm sorry if I bothered you with this problem and I'd like to thank you for taking your time to help me.