Where did you go?"" ""Out."" ""What Did You Do?"" ""Nothing.""- was the nostalgic surprise best seller of the Fall season. Every puzzled parent who wanted to share his sons' experiences found some of the answers in this boyhood recall. Kids aren't so different today. BUT we wonder whether there are many of today's kids who will read this through and then go back to it for the things to make out of nothing -- and how to put them to use once they are made. Perhaps the earlier book launched a back-to-fundamentals urge, a get-rid-of-this-organized-program feeling. Anyhow, here's how -- whether to make a spool tank, a paper-folded airplane, a sling shot, a basket out of burrs, a rubber band gun or what have you. There are step by step instructions for mumbly-peg -- all 20 variations (I always stuck at Johnny Jump the Fence). To bring it down to the simplest definition, this is the how-to book for the boys whose fathers can't quite remember.