See this thread for more details:
Maple seeds wont sprout
If the climate in your zone is suitable, the easiest method is to harvest the seeds in the fall when the samaras (wings) start to brown, plant in pots or trays 1/4 inch (or less) deep, and leave outside all winter in an area protected from rodents and other pests. With any luck they will sprout in the spring.
If you have the time and the inclination, the methods detailed in the link above may produce better results, at the expense of more effort.
Good luck.
