If you're new to weight lifting, you typically will want to try a linear progression in order to make the fastest gains.
1. For each exercise, pick a set/rep combination appropriate for your goals, training experience and exercise. For example, if you are relatively new to lifting and just trying to build strength, 3-5 sets of 1-5 reps tends to be most appropriate. We'll use 3x5 as the example here.
2. Each time you walk into the weight room, you have a target weight X for each exercise. If you complete the 3x5 with X lbs, the next time you do the exercise, add Y lbs and try to do a 3x5 again. Continue adding Y lbs each workout until you get stuck (see step 3). The value of Y depends on the exercise - for something like deadlift, a newbie could add 10-20lbs each time. For the OH press, however, it's typically hard to add more than 2-5lbs per workout.
3. If you get to some weight X where you can't quite finish all 3 sets of 5, re-try the same weight on the next 2 or 3 workouts. If you get it then, continue increasing weight as indicated in step 2. If after ~3 tries, you still can't get all 3x5, do a soft deload. This means reducing the weight by ~10% and working your way back up over the next several workouts. This usually lets you break through plateaus. If after a soft deload, you're still stuck, try a hard deload - it's roughly the same thing, except you reduce the weight by ~20%. If after soft & hard deloads, you can no longer make linear progress on your lifts, you are probably done with the beginner stage and a linear progression will not work for you any more. At this point (which I doubt you'll get to in 1.5 months), you'll need to seek an intermediate program which focuses on making gains on a weekly basis rather than every single workout.
Also, I hope your workout includes more than just bicep curls