For your specific question, from what I remember from college, your weight training is going to be dependent on what part of the season you are in, and is going to be a progressive thing. So, for your off season, you will be doing sets in the 8-10 rep range, and as your season progresses, so will the weight and the reps will start dropping down.
For other considerations, you will probably want to add serious core work, plyometrics, agility. Strength is a key part of the discus, but balance through the spin, being able to translate that spin into the motion with a coordinated toss, etc. are going to matter just as much as how strong you are. I would highly recommend finding a coach that can teach you all aspects of the training and techniques.
Here's a few references I found for exercise programs. The one from brianmac outlines more of what I was talking about, the other one strictly addresses weights.