Our local saying is: "It takes 3-4 years to make a racer".
Here's some steps:
- Join a local club. Tell them you're new and would like to get into racing.
- Find a competent bike shop. Give them the business you can. Hang out every once-in-awhile. Don't annoy the people there by getting in the way of them doing their jobs. Tell them you're new to the sport, and would like to get into racing.
- Ride with others. These would be called "group rides" and are very important in the development of your bike handling skills.
- Find a junior development team to join/ride with. Use your new contacts/friends at the bike shop or club to find out which are the good ones.
- Ride lots. In the beginning, putting in the hours on the bike is the best/fastest way to get in race shape.
Also, don't lift weights using upper body muscles. It only adds bulk. (In cycling, weight is the enemy.) Any strength gains you get will come from the simple fact of you moving weights around getting the equipment set up for the leg exercises.
At your age, running is okay, but if you want to go far in this sport, eventually you'll want to drop that as well so you can concentrate on cycling. However, if you plan on doing triathlons... that's a different beast and running/swimming will benefit you.
In thinking about your riding, focus on "hours" not miles. It'll help you down the road.
At 16, you're kind of hitting the sport late for a junior and are at a slight disadvantage. Next year's 17-18's who are already racing? Some are already cat 1's & 2's--the top end of the sport. The 16 year-olds aren't too far behind (cat 3's & 2's). If & when you get dropped in your first race, don't get discouraged & give up! Every racer every where has gotten dropped at one point or another. It's what you do next that determines your success. Get back on the bike, and race again. Eventually, you'll keep up and maybe even get some wins along the way.
Good luck.