By Sue Goldfarb He believes in moving, not sitting. PALO ALTO, Calif. – At the tender age of 21, Brett Kingstone turns ideas – his own and others’ – into money. He calls himself “a simple shmo.” He writes guest editorials for the Wall Street Journal at $1,000 a crack. He’s collecting $100,000 in royalties this year from the how-to-do-it …