Not hugely helpful!
I'm no VB
person either - I know bits but wouldn't want to give actual example code in case I got something wrong and confused you.
Essentially though the idea is to check the state of the textbox each time the user presses a key. So instead of capturing when the user presses a key and acting on that directly, you'd capture when the user presses a key, check the contents of the textbox is equal to "hello", and if it is you can do something. If not you just wait for the next key to be entered.