See the section on 'Advanced Features' for doing some really fancy stuff like this. But for the basic insert function:

From Page 72 in the manual:

You can insert the value of a subject’s prior response to any fill-in-the blank or scale response item by typing the appropriate variable name surrounded by < > within any question wording text. For example, if you had previously asked subjects about their race using a fill-in-the-blank question or a scale response and you had called this variable race, then you could insert the subjects response in a subsequent question wording like this: What percentage of your friends are <race>? For scale responses, the text label of the selected response is used.