screw up from the bottom of the wood into the pipe. when you co this make sure you secure the pipes to the wood so they don't slip. i just taped the pipes on the ends and in the middle.
hey man if you dont want to worry about screws and such i would use 'liquid nails glue' i tried it out and it works beautifully there is no way that pvc will ever budge. im not even exagerating