Where can I find documentation regarding framing a gable on my front porch?

Answer 1

p. 361 in Architectural Graphic Standards -10th Edition - Ramsey/Sleeper

and page 6.28 in Building Construction Illustrated - 3rd Edition - Ching

Both are really good references!

Answer 2

Make it easy, buy a truss- set it in front, then nail the ridge board to it, then cut the rafters the same as the angle on the truss- //// 2. Set the Ridge the hight you want it to be, trim it to the outside wall- then hold the Rafter across the front of it, mark the Angle on both sides by doing the same. Set the Rafters 2 ft on center.

If this is not clear, buy a Framing book.