Perhaps you could express yourself better. What exactly do you mean? Do you want an app that will write an ebook for you? Surely not! Instead of 5 million ebooks currently on sale we would have gazillions. It doesn't even bear thinking about.
Do you perhaps mean you want an app that will convert what you have written into an ebook? Or an app that will convert your epubs into a format that can be read on a Kindle Fire tablet? Try this website:
Lulu's links seem to be playing up. If it doesn't work copy this link into your browser's URL bar.
or simply Google 'how to read epubs on a Kindle Fire tablet'
As danielblue said, not sure what you're asking for. If you want to put an epub file on your Kindle, you can download Calibre (it's a free program) and it will convert your file. I use it all the time for both my Fire and Paperwhite. You can also send your epub file to your device using http://www.sendepubtokindle.com/. Your Kindle has an e-mail address, you can find it on your account page under "manage your devices."
Not to worry because the OP asked in two other threads also ..