To sprint or ride fast needs more than just one month ride. You have stated that you don't have hills so intervals will be your way of stamina building. Everyone has his way of doing things. I would recommend you start with a cadence training. Locate a flat stretch of road and using a light gear pedal as fast as you can for about a minute. Note that you shouldn't bounce or get off the saddle. spin lightly as you go back for another run. Am not an expert in giving advices but this should get you started.