Scrolling Text on the Ground

Im sure a few of you here knew who ChrydGod was and probally remember his awesome Cube Defense.

Lately I've been trying to figure out how to do the scrolling text on the ground thing here did. I know JASS sorta anyway, but some of it, the complicated stuff ( to me anyway) gets me confused. I was looking over his map and I found where most of his stuff for it is, but was wondering if somone could help me figure out how to use what he did to display a message on the ground like "Place Unit Here" or somthing.