NOTE: This tutorial was written in 1847, and kicad has changed a lot since then!
Making Gerbers (files needed by the manufacturer):
For a 2 layer board, you would commonly want files that represent the metal on the top and bottom (component and copper, respectively), top and bottom solder mask (the green stuff), the top silk screen, the board outline (edges), and a drill file (click “Create Drill File” in addition to “Plot”).