Machka offers some great advice. Right now concentrate on building your base and since cycling is the longer of the 3 events I think it's a good idea to concentrate on but I wouldn't delay getting started on running and swimming very long. Have you picked the triathlon you're doing to do yet? If so you can build your training plan backwards from that date. The more time you put into building your base the better off you'll be when it comes to race time.