If you are starting from scratch and clueless with weights, probably most of these responses don't mean a lot to you.
If you are serious about improving upper body strength, you need to take a serious approach. If you meander around a gym aimlessly doing different weights at random, your programme has no structure to it and you won't notice results.
I would advise you see a professional or someone you know who has a lot of experience with weights and knows what they are doing. It is possible to see a personal trainer for a couple of sessions to get you started, learn the basics, get them to give you a structured weights programme and then work on this programme by yourself.
It really isn't complicated and doesn't need to be just to build up upper body strength, but it would help you to have someone who knows what they are doing show you as technique is really important when working with weights so you don't injure yourself.
So get someone to show you the exercises. Probably best to work on 3-4 sets of 8-12 reps with a minute rest between each set as someone mentioned earlier.
So for example you might start with shoulder press. Pick two dumbells and figure out what is the right weight so you can do more than 8 but no more than 12. Then do 3 sets with a minute break in between each. By the third set you may be struggling to do 8 but just do as many as you can.
The important thing about improving strength is to push yourself every single time. Every time you do this programme you should try and do an extra rep. I take a little diary with me to the gym and I write down what weight i lifted and how many reps. So I know next time what i have to improve on. When you can do 12, then move up to a heavier weight and go through it all again.
If you structure it you will definitely improve your strength. Even over a few weeks you will definitely notice a difference.
Most important thing anyone ever taught me was to write it down. And keep it structured. This should be easy for an ESTJ!
After a weights session, your muscles need protein, so either eat some form of protein as soon as possible after the session (preferably within 20 mins) Or buy a tub of Whey Protein powder and mix with water and drink after your session. It is the easiest way and if you buy plain whey protein, it is just like eating a chicken breast, it isn't like some kind of get massive body building supplement. And your muscles will need protein to get stronger.
Overall though, I would suggest you get someone to show you how to use weights as it can be kind of scary the first time and there is a risk of injury if you don't get the technique right. Once you know what you are doing though, it is very straightforward and addictive!