Beardking is right. tracing is probably one of teh better ways to go..

Raster images are usually made up of colourd blocks; pixels. While vectors are lines drawn from a data base with two end points; coordinates, hence a vector..

CAD programs can be set up with the wood sizes, but it'll be better to just remeber them. Typically, you'll be making three dwgs, that all tie together: a top view, a side view, and possibly a front view. that is, a 2D drawing of teh plane. Other views will be created as teh work progresses.. Most CAD programs have an 'Offset' function, that offsets (copies) a line /object a certian amount. So, you'll draw the center lines for ribs, stringers, spars, etc.. then jsut offset them as required. (tip: work on a separate layer, so your center lines are on one layer, and the 'wood' is on another..) Everything needs to be drawn....

Ideally, you'll also have Excell or a pad of paper beside you and start a parts list.