Congratulations first off on your winnings! Welcome to the beginning stages of your body transformation, it's going to be great watch! Now, right of the bat, there is no sure fire way to calculate proper weights for your workouts. You just have to listen to your body and be sure to not push beyond what your body is telling you what it can handle. It's ok to start of slow and light to make sure you develop great form. Without proper form you are wasting your time and potentially damaging your body in the long hull.
As far a program goes...that depends on your body type, genetics, stamina, motabolism, etc. I would say, from what you wrote you are looking to gain mass and specifically you want to gain lean mass (which is a sculpted body frame and physique). If this is the case then I would encourage you to focus body fat percentages and not total weight. If you want to weigh in at 185lbs in the end then you should shoot for a 10-12 body fat percentage with your total body weight. What this means is that out of your total body weight of 185lbs only 10-12% of that is fat and the rest is lean muscle mass so the translates to roughly having 18.5-20lbs of fat on your body while the remain weight is lean muscle. Does that help?
You might want to start with lifting heavier weights (what you can handle for right now) with low repeptitions ( 3 sets of 6-8 reps for example) and work on increasing the weight as you go but keep the reps the same or even lower them if need be.
Check out the workout plans that are posted here, they are a great place to start! Congratulations again!