Well the event you are going to want to checkout is the KeyDown event of a control. This event has a parameter called "e" which is passed to it when the user presses a key or a series of keys. You can use the properties "keycode", "keydata", "keyvalue", and "modifiers" to determine the keys pressed on the control. With the combination of these properties with the modifiers property you can determine key combinations like the shift or alt keys etc.
In this event you can detect the keys pressed and simply modify controls with whatever content you want to display for that key. Like inserting a happy face image when they type ":)"
For more information about the event and how to use its properties, you can check out this MSDN page...
Control.KeyDown Event - MSDNHope that is what you were looking to do. Enjoy!