somebody pleeeease help me?

Ok, I´ll write this in engilsh so all my reader will understand: )
Where is this dress from?
I found it on my computer, but I really dont know where I found it, and I dont know when I found it. Crisis.
It is gorgeous, and it would be perfect for my confimation in April! : D

So if you have seen this in a store ore online, please tell me where! I am desperate : )

thanks for your time;- )