Create Twitter Header

I need a page that allows visiters to create their own twitter header and then watermark my logo or web address to their image. It would be great if they could auth to use the app and it would automatically change it for them, and also send out a tweet from where they got it. But I MAINLY want visitors to be able to go to my website and create their own header from any image and add effects or text. This should be something simple. it should function someone like [login to view URL] thanks