Check out the PAF construction method below.  The pictures are samples from the P-40 and f4u instructional manual - Really simple, easy, and VERY THOROUGHLY EXPLAINED.  All you really need to get started is a good comfortable pair of scissors and some glue.    Just like the real planes, the airframe derives its stability from the tensile strengh of the skin itself, and the construction is similar to the process used with actual sheet metal.