Biathlon- I need information to get ready for this event

When I was training for my first marathon, I read somewhere there is a quantifiable number of seconds on how each pound of body weight will affect your times. I then read recently that weight lifting more than about two-three times a week is counterproductive for endurance performance.

With that in mind, RUN and BIKE. One method to consider is overrunning and overbiking. It goes like this. On weekends, you have your long runs/bikes. Your mileage monday through friday should equal at least what you are planning to do on your long run/bike. And for a 5 mile run, 22 mile bike, consider doing a 5.5 - 6.0 mile run for your long run, with a 24-25 mile ride for your long ride. And make sure that you do BOTH the ride and the run on the same day, preferably back to back.

September 19 isn't that far away, so your mileage should already be up there (running at least 3-4 and riding 15-17 at one go...)

There are many training plans on freely available on the internet. Find a good one and stick with it, but be a little flexible-life does come at you fast. And most important, don't give up-you CAN do it!