InfoPath Dev

How do I make a text box appear when a certain dropdown selection is made? When I try to create a rule I don't know how to call on that particular text box in the rule. Your help is much appreciated.

Your text box is bound to a field - so is your dropdown. In this case, the rule needs to go on the text box - add a formatting rule to hide it unless the value of the dropdown is what you want. I've attached a sample - save the file locally, right click and select Design. From there, you can see the rule on the textbox & you can preview the form to see how it behaves.