Reply to topic redirect

First topic message reminder :

I'd like to ask for a little help if possible, I'm creating an HTML page i have a box in it, when you press send, it should post what you wrote down in a certain topic, Like once you hit the "Send" button it will post your message in a topic as a reply to it
this is the HTML page http://cda-academy.forumotion.com/h2-market 

Once you press send it will show you this http://gyazo.com/6d673c72a6036d86f31d5088cabf8802 how can i fix that? to make it post what you wrote in that box in a certain topic ? also how can i change the background image of that HTML page to a certain image or just make it all black?

Thanks in advance!

It works!

Spoiler:

Solved