Many folks have built wood gasifiers already, and can help you out with yours. They are actively discussing their projects in the forums. There you can see what folks like you have done and ask questions.
You'll find lots of free info on woodgas. Everything from the basics of gasification through advanced fluid dynamics. Much of the research available on gasification is available as free PDF downloads.
Wayne Keith has detailed tutorials & in depth articles on how to build his gasifier. Follow step by step construction videos from start to finish! Premium members also get Wayne's book Have Wood Will Travel.