Topic awaiting preservation: Q+A Forms

How can i create a question and answer form, i.e if i type hello in a text box and click a button it replies 'hello', but if i type goodbye in the same textbox i want it to reply 'goodbye' instead of 'hello' again.. Thanks

If the button in question is pressed run a function that checks whether the word written in the textbox is "hello" or "goodbye". If the word is "hello" print "hello" to the screen, same thing with "goodbye".