Below that, in the <Instance Name> field, type a name for your text box; I named mine, predictably, "scrollbox". It needs an instance name because we're going to be referencing it by name in our Actionscripts.
Last but not least, click on the dropdown that says "Single Line" and select "MultiLine". If your text is set to single lines, then it won't wrap to fit the window; it will just extend off to the side and vanish until the next line break. Telling Flash that you have multiple lines causes the text to automatically advance to the next line when it reaches the edge of the bounding box.
