i know this seems a stupid question, i am new to triathlon, but do you have to do any weight trainning, or just concentrate on running swimming and cycling.
I am not an expert myself but I gather from lots of reading that weight training is not essential but it can be benificial. Although weight training is generally done in the off season.
Hey, while you're starting out I really wouldn't worry about weights at all, just enjoy it. You'll find you get naturally stronger as you get fitter. Even when you've been in the sport for a while I wouldn't rely on weights very much. I think there is a tendency to use weights to get big rather than get strong and there is quite a difference. In an endurance sport you don't want big muscles to carry around but you want strength to keep going. This kind of strength can be gained from things like hill reps on the bike and run and paddles and band work in the pool. This way the strength you develop is specific to the actual motion rather then big muscles which can do the same thing but in a less efficient way.
I believe weight training can be benefical if you do relevant training. So you are not training to put on bulk and get big muscles to carry around but to improve your power output. If you look in the normal triathlon training books (Joe Friel etc) you will find useful weight training programs.
If you are just starting out, depending on your level of fitness and time available for training, the chances are you would be better off spending the time on your CV fitness.