Having found this website, you have broken the seal on the King Tut's Tomb of primitive archery lore and knowledge. A good next step would be to subscribe to Primitive Archer Magazine just so that the constant input of articles and stories will keep the fire stoked. Then you may want to visit the many advertisers on this site to pick up a copy of the Traditional Bowyer's Bible, volume 1. That book has more information in it than you will be able to soak up in 5 years. It even has a chapter devoted to making a bow from a board.
Pay particular attention to that chapter, follow it closely, and you will be able to knock out something fairly usable with your first effort. Be sure, of course, to post pictures of your progress here on the Primitive Archer forum....and then we will digitally mentor you thru the process.
Welcome to the addiction!